Methods, systems and apparatus for determining whether an accessory includes particular circuitry

ABSTRACT

Methods, systems, and apparatus for determining whether an accessory includes particular circuitry. A host device may measure a first voltage and a second voltage received from an accessory, where the voltages are provide through the accessory from a power source. Before measuring the second voltage, the host device may send an instruction to the accessory instructing the accessory to alter an impedance of the power path between the power source and the host device, and the host device may draw at least a threshold amount of current from the power source via the accessory. The host device may then determine whether the accessory includes particular circuitry based on the relationship between the first voltage and the second voltage.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/607,473 filed on Sep. 7, 2012, which claims the benefit of U.S.Provisional Patent Application No. 61/635,652, filed Apr. 19, 2012, andentitled “METHODS, SYSTEMS AND APPARATUS FOR DETERMINING WHETHER ANACCESSORY INCLUDES PARTICULAR CIRCUITRY,” both of which are incorporatedherein by reference in their entirety for all purposes.

This application is also related to U.S. patent application Ser. No.13/690,955, filed Sep. 7, 2012, and entitled “METHODS, SYSTEMS ANDAPPARATUS FOR ENABLING AN ACCESSORY FOR USE WITH A HOST DEVICE,” whichis incorporated herein by reference in its entirety for all purposes.

BACKGROUND

Embodiments of the present invention generally relate to host devicesand accessories. More particularly, embodiments of the present inventionrelate to techniques for determining whether an accessory includesparticular circuitry as well as techniques that enable a power pathbetween a power source and a host device.

Cables are one type of accessory that are often used to connect a hostdevice, such as a mobile phone, a personal digital assistant, a mobilecomputer, etc. to a power source. The cable may then operate to transferpower from the power source to the host device so as to charge the hostdevice, provide operating power to the host device, and the like. Othertypes of accessories, such as docking stations, similarly operate totransfer power from a power source to the host device by way ofconnecting the host device to the accessory. This may be done, forexample, by connecting a connector of the host device to a connector ofthe accessory.

As a result of their power transferring functionality, such cables andother accessories inherently provide a risk of injury to users by, forexample, electric shock. Such risks may increase due to particularconnector designs (e.g., where the cable or other accessories have aconnector with exposed leads for connecting to the host device), due toincreased voltages and currents which may be desired to, e.g., increasea charging speed of the host device, and/or due to sub-par quality ofmanufacturing of the accessories. Such cables and accessories maysimilarly provide a risk of damage to devices connected thereto. In manyinstances, these risks also exist due to cables or other accessoriesmaintaining a voltage potential even after being disconnected from thehost device.

Accordingly, it is desirable to provide systems, methods, and apparatusthat reduce the likelihood of electrical shock resulting from use ofsuch accessories.

SUMMARY

Embodiments of the present invention are generally directed to hostdevices and accessories and methods of operating host devices andaccessories. In particular some embodiments of the present invention aredirected to determining whether an accessory includes particularcircuitry, such as power limiting circuitry, and operating a host devicebased on whether the accessory includes the particular circuitry. Someembodiments are also directed to establishing power paths between powersources and host devices.

In accordance with some of the methods described herein, a host devicemay be operable to determine whether an accessory includes particularcircuitry. This may be done by measuring, at a host device coupled to anaccessory, a first voltage received from the accessory via a power pinprovided in the host device. The host device may then send aninstruction to the accessory to alter an impedance, at the accessory, ofa power path between a power source and the host device, and thenmeasure a second voltage received from the accessory via the power pinprovided in the host device. The host device may then determine whetherthe accessory includes particular circuitry based on the relationshipbetween the first voltage and the second voltage.

In accordance with other embodiments for determining whether anaccessory includes particular circuitry, a method includes measuring, ata host device coupled to an accessory, a first voltage received from theaccessory via a power pin provided in the host device. The host devicemay then sink current from a power source via the accessory, and measurea second voltage received from the accessory via the power pin providedin the host device. The host device may then determine whether theaccessory includes particular circuitry based on the relationshipbetween the first voltage and the second voltage.

In addition to the methods of operating host devices and appliancesdescribed herein, embodiments are also directed to host devices. Hostdevices according to various embodiments may include a number ofelements, such as power pins, data pins, and control circuitry. Forexample, a power pin may be operable to receive a voltage from anaccessory. A data pin may be operable to communicate variousinstructions to the accessory. The control circuitry may be operable toperform a variety of functions, such as measuring voltages received viathe power pin, sending instructions to the accessory via the data pininstructing the accessory to alter an impedance, at the accessory, of apower path between a power source and the host device, and sinkingcurrent from the power source via the accessory. The control circuitrymay also be operable to determine whether the accessory includesparticular circuitry based on the measured voltages.

In addition to the embodiments directed to various methods and to hostdevices, embodiments are also directed to accessories. Accessoriesaccording to various embodiments may include a number of elements, suchas power pins, data pins, and power limiting circuitry. The power pinmay be operable to provide a voltage to a host device. The data pin maybe operable to receive various instructions communicated from the hostdevice. The power limiting circuitry may be operable to alter animpedance of a power path between a power source and the host device inresponse to receiving an instruction from the host device, and reducethe voltage provided to the host device from the power source when athreshold amount of current is drawn through the power limitingcircuitry.

For a fuller understanding of the nature and advantages of embodimentsof the present invention, reference should be made to the ensuingdetailed description and accompanying drawings. Other aspects, objectsand advantages of the invention will be apparent from the drawings anddetailed description that follows. However, the scope of the inventionwill be fully apparent from the recitations of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a system for determining whether an accessoryincludes particular circuitry according to an embodiment of the presentinvention.

FIG. 2 is a schematic of power limiting circuitry according to anembodiment of the present invention.

FIG. 3 is a schematic of impedance altering circuitry according to anembodiment of the present invention.

FIG. 4 is a graph illustrating a voltage/current characteristic of powerlimiting circuitry operating in a bypass mode according to an embodimentof the present invention.

FIG. 5A is a graph illustrating a voltage/current characteristic ofpower limiting circuitry operating in a power limiting mode according toa first embodiment of the present invention.

FIG. 5B is a graph illustrating a voltage/current characteristic ofpower limiting circuitry operating in a power limiting mode according toa second embodiment of the present invention.

FIG. 6 is a schematic of control circuitry in accordance with anembodiment of the present invention.

FIG. 7 is a schematic of power control circuitry in accordance with anembodiment of the present invention.

FIG. 8A is a flowchart of a process for operating a host deviceaccording to an embodiment of the present invention.

FIG. 8B is a flowchart of a process for a host device to establish aconnection with an accessory according to a first embodiment of thepresent invention.

FIG. 8C is a flowchart of a process for a host device to establish aconnection with an accessory according to a second embodiment of thepresent invention.

FIG. 8D is a flowchart of a process for determining whether an accessoryincludes power limiting circuitry according to some embodiments of thepresent invention.

FIG. 9A is a flowchart of a process for operating an accessory accordingto an embodiment of the present invention.

FIG. 9B is a flowchart of a process for an accessory to establish aconnection with a host device according to some embodiments of thepresent invention.

FIG. 9C is a flowchart of a process for an accessory to respond toinstructions provided by a host device according to some embodiments ofthe present invention.

FIG. 10A illustrates a system for determining whether an accessoryincludes particular circuitry according to a first embodiment of thepresent invention.

FIG. 10B illustrates a system for determining whether an accessoryincludes particular circuitry according to a second embodiment of thepresent invention.

FIG. 11A illustrates a plug connector according to an embodiment of thepresent invention.

FIG. 11B is a simplified, cross-sectional view of the plug connectoraccording to an embodiment of the present invention.

FIG. 11C is a cross-sectional view of the plug connector according to anembodiment of the present invention.

FIG. 11D is a cross-sectional schematic view of a single-sided plugconnector according to an embodiment of the present invention.

FIG. 11E is a pin-out of a plug connector according to an embodiment ofthe present invention.

FIG. 11F is a pin-out of a plug connector according to anotherembodiment of the present invention.

FIG. 12A illustrates a receptacle connector according to an embodimentof the present invention.

FIG. 12B is a cross-sectional view of the receptacle connector accordingto an embodiment of the present invention.

FIG. 12C illustrates a cross-sectional view of a receptacle connectorhaving sixteen signal contacts and four connection detection contactsaccording to an embodiment of the present invention.

FIG. 12D is a cross-sectional view of a receptacle connector havingeight signal contacts and two connection detection contacts according toan embodiment of the present invention.

FIGS. 12E and 12F are diagrams illustrating a pinout arrangement of areceptacle connector according to two different embodiments of theinvention configured to mate with plug connectors 700 and 701,respectively, as shown in FIGS. 11E and 11F.

DETAILED DESCRIPTION

Embodiments of the invention are discussed below with reference to FIGS.1 to 12F. However, those skilled in the art will readily appreciate thatthe detailed description given herein with respect to these figures isfor explanatory purposes only as embodiments of the invention extendbeyond these limited embodiments.

Systems, apparatus, and methods described herein are generally relatedto controlling host devices and accessories, and in some casesdetermining whether an accessory includes particular circuitry such aspower limiting circuitry.

“Accessory” should be broadly construed to include any one or more of avariety of electronic components, such as a cable, a docking station, analarm clock, a radio, a speaker set, a charging station, etc. Ingeneral, an accessory can be any device that is operable to be used witha host device. In some embodiments, the accessory may include hardwareand/or software operable to influence a power path between the hostdevice (e.g., an iPhone™) and a power source. In some cases, the powersource may be included in the accessory (e.g., when the accessory is acharging station), and in other cases the power source may be externalto the accessory (e.g., when the accessory is a cable). Accordingly, theaccessory may actively provide power or passively transfer powersupplied from an external power source.

In some embodiments, a host device may determine whether an accessoryincludes particular circuitry such as power limiting circuitry and thenperform various operations based on the result of such a determination.For example, the host device may refuse to charge via the accessory ifthe accessory does not include power limiting circuitry. In such cases,the use of accessories which may increase risks of harm to users anddamage to host devices may advantageously be reduced.

Whether an accessory includes particular circuitry may be determinedusing any one or more of the techniques disclosed herein. In general,methods for determining whether the accessory includes particularcircuitry may be based on the host device selectively measuring anelectrical characteristic, such as an impedance, of the accessory. Inone particular embodiment, this characteristic may be measured by firstmeasuring a property of the accessory, then sending an instruction tothe accessory for the accessory to change one or more of its properties(e.g., increase its impedance), and then measuring the property of theaccessory once again to see whether the accessory understood theinstruction and includes the proper circuitry for changing itsproperties. In some embodiments, the host device may include a currentsink to force a certain current to be drawn through the accessory,whereby the host device may then determine whether the accessoryincludes the particular circuitry as the current sink will place theaccessory into a known state (if it includes the particular circuitry).

Once it is determined whether an accessory includes the particularcircuitry, the host device may perform additional operations. In someembodiments, power consumption by the host device from the power sourcemay be controlled based on this determination. For example, if it isdetermined that the accessory includes power limiting circuitry havingcertain characteristics, the host device may receive power from thepower source via the accessory, perhaps for operating internal circuitryof the host device and/or charging an internal battery of the hostdevice. On the other hand, if it is determined that the accessory doesnot include the power limiting circuitry, the host device may refuse toreceive power from the power source via the accessory. In this fashion,the host device may only charge and/or operate with accessoriesdetermined to include power limiting circuitry so as to advantageouslyreduce the likelihood of consumer use of accessories that may notsatisfy desired specifications.

Also described herein are techniques for establishing a connectionbetween a host device and an accessory. Such techniques may be used to,for example, facilitate communication between the host device and theaccessory and/or establish a power path between a power source and thehost device via the accessory. In one embodiment, the host device maysend requests for an accessory identifier on a first data pin of thehost device and if a valid accessory identifier is not received inresponse thereto the host device may try sending such requests again ona second data pin different from the first data pin. On the other hand,if a valid accessory identifier is received, the host device may beginto receive power from a power source via the accessory. In some cases,while the host device may begin to receive power after receiving a validaccessory identifier, the host device may then either continue ordiscontinue receiving such power after determining whether the accessoryincludes power limiting circuitry.

Turning now to the figures, FIG. 1 is a schematic of a system 100 fordetermining whether an accessory includes particular circuitry accordingto an embodiment of the present invention. In this embodiment, system100 includes a host device 110, an accessory 120, and a power source130.

Host device 110 may be any suitable electronic device that is operableto perform the functionality discussed herein, and may include one ormore hardware and or software components operable to perform suchfunctionality. For example, host device 110 may be a mobile phone, apersonal digital assistant (PDA), a handheld or portable device (e.g.,iPhone™, Blackberry™, etc.), a notebook, a personal computer, a notepad, a tablet computer, a media player (e.g., a music player or videoplayer), a camera, a game player, a laptop computer, a netbook, abooklet, or other electronic device configured for wired or wirelesscommunication.

Host device 110 includes control circuitry 111 and a connector 112,where control circuitry 111 is electrically coupled to connector 112 andoperable to perform some or all of the operations discussed herein withreference to host device 110. Host device 110 may include additionalcomponents (not shown), such as a tangible computer-readable storagemedium, power source (e.g., a battery), etc., such that host device 110may be operable to perform one or more of the functions discussed hereineither in hardware and/or via instructions stored on the storage mediumexecuted by control circuitry 111. Connector 112 includes one or morepins electrically coupled to control circuitry 111, such as a power pin113, a data pin 114, and one or more additional data pins 115. In someembodiments, power pin 113 may be electrically and/or mechanicallycoupled to control circuitry 111 so as to communicate a voltage or otherpower to control circuitry 111 provided by accessory 120. Data pin 114may also be electrically and/or mechanically coupled to controlcircuitry 111 so as to facilitate data communication between controlcircuitry 111 and accessory 120. The one or more additional data pins115 may also be electrically and/or mechanically coupled to controlcircuitry 111 so as to facilitate data communication between controlcircuitry 111 and accessory 120. In some embodiments, data pin 114 maybe arranged to couple to power limiting circuitry 121 of accessory 120,while the one or more additional data pins 115 may be arranged to alsocouple to power limiting circuitry 121 or different circuitry ofaccessory 120.

Accessory 120 may be any suitable electronic device that is operable toperform the functionality discussed herein, and may include one or morehardware and or software components operable to perform suchfunctionality. For example, accessory 120 may be a cable, an alarmclock, a radio, a speaker set, a docking station, an input device suchas a keyboard, a musical instrument such as a digital piano, a battery,a charging station, an image/video projection unit, or other deviceoperable to source power to the host device or transfer power to thehost device provided by a power source external to the accessory.

Accessory 120 includes power limiting circuitry 121 and a connector 122.Accessory 120 may include additional components (not shown), such as atangible computer-readable storage medium, power source, etc., such thataccessory 120 may be operable to perform one or more of the functionsdiscussed herein either in hardware and/or via instructions stored onthe storage medium executed by a processor. Connector 122 includes oneor more pins electrically coupled to power limiting circuitry 121, suchas a power pin 123 and a data pin 124. In some embodiments, power pin123 may be electrically and/or mechanically coupled to power limitingcircuitry 121 so as to communicate a voltage or other power from powerlimiting circuitry 121 to power pin 113 upon engagement of connector 122with connector 112. Data pin 124 may also be electrically and/ormechanically coupled to power limiting circuitry 121 so as to establishdata communication between power limiting circuitry 121 of accessory 120and control circuitry 111 of host device 110 upon engagement ofconnector 122 with connector 112.

Power source 130 may be any type of device operable to source power,voltage, and/or current, such as a battery, an AC/DC converter, an ACelectrical outlet, a power supply, etc. Power source 130 may be internalor external to accessory 120. In FIG. 1, power source 130 is depicted asbeing external to accessory 120. In any case, power source 130 isprovided such that power limiting circuitry 121 is disposed in a powerpath between power source 130 and host device 110. For example, powerlimiting circuitry 121 may be electrically and/or mechanically disposedbetween power source 130 and power pin 123 of connector 122.

Host device 110 and accessory 120 may be operable to perform a varietyof functions as discussed herein. In one embodiment, host device 110 maybe operable to establish a connection with accessory 120, determinewhether accessory 120 includes power limiting circuitry 121, and thenbased on the outcome of that determination perform various actions. Forexample, upon establishing a connection with accessory 120, host device110 may receive power from power source 130 via accessory 120. Then,upon determining whether accessory 120 includes power limiting circuitry121, host device 110 may decide to either continue receiving power frompower source 130 or discontinue receiving power from power source 130.In such a fashion, host device 110 may be controlled based on whether ornot accessory 120 includes specific circuitry having specificproperties.

To establish a connection with accessory 120, in one particularembodiment, upon physically engaging host device 110 and accessory 120by coupling connector 122 with connector 112, control circuitry 111 maysend a request for an accessory identifier to accessory 120 via data pin114. Control circuitry 111 may then monitor data pin 114 to determinewhether a valid accessory identifier is received from accessory 120. Ifnot, control circuitry 111 may re-send the request. In some embodiments,the request may be re-sent on another data pin (such as one ofadditional data pins 115). For example, connector 112 and connector 122may have multiple connection orientations whereby they may be physicallyconnected with one another in more than one orientation. In some cases,in a first orientation data pin 114 may be in contact with data pin 124.In a second orientation, data pin 114 may not be in contact with datapin 124, but another data pin such as an additional data pin 115 may bein contact with data pin 124.

At accessory 120, power limiting circuitry 121 may monitor data pin 124for power and/or requests. For example, in one embodiment, power may becommunicated from host device 110 to accessory 120 via data pin 124.This power may be used for accessory 120 to operate in the eventaccessory 120 cannot acquire operating power from other sources such aspower source 130 or does not have an internal power source. If power isnot received, then power limiting circuitry 121 may continue to monitordata pin 124. However, if power is received, then power limitingcircuitry 121 may disable a power path between power source 130 and hostdevice 110. In some cases, the power path may be disabled by default,and thus further disabling may be omitted. Once the power path isdisabled, power limiting circuitry 121 may receive and read the requestfor an accessory identifier. If the request is valid, then powerlimiting circuitry 121 may send an accessory identifier to host device110 via data pin 124, and enable (or re-enable) the power path betweenpower source 130 and host device 110. Otherwise, power limitingcircuitry 121 may continue to monitor data pin 124.

Once a connection has been established between host device 110 andaccessory 120, the power path between power source 130 and host device110 may be enabled. In some embodiments, this may allow host device 110to acquire an operating charge, such as when the host device 110 doesnot have sufficient power to operate a main processor to executesoftware provided in the host device 110 (e.g., it has a dead battery).In other embodiments, host device 110 may have sufficient power tooperate such software, in which case it may choose to continue operatingusing its own power or begin to operate using power supplied via thenewly enabled power path. In any case, once host device 110 is providedwith operating power, host device 110 may determine whether accessory120 includes power limiting circuitry 121. To do this, control circuitry111 may measure a first voltage received from accessory 120 via, forexample, power pin 113. This first voltage sets a baseline forcomparison. Control circuitry 111 may then send an instruction to theaccessory to alter its impedance (e.g., alter the impedance, at theaccessory, of a power path between power source 130 and host device 110)and/or sink current from power source 130 via accessory 120. Theinstruction may be sent via data pin 114, while current may be sinkedvia power pin 113. Once control circuitry 111 performs one or both ofthese functions, control circuitry 111 may then measure a second voltagereceived from accessory 120 via power pin 113. The first voltage maythen be compared with the second voltage to determine whether accessory120 includes power limiting circuitry 121. If the first voltage isgreater than or less than the second voltage, control circuitry 111 maydetermine that accessory 120 includes power limiting circuitry 121.Otherwise, control circuitry 111 may determine that accessory 120 doesnot include power limiting circuitry 121.

If accessory 120 includes power limiting circuitry 121, accessory 120may understand and respond to the instructions sent by control circuitry111. For example, power limiting circuitry 121 may receive aninstruction, via data pin 124, for accessory 120 to alter an impedanceof the power path between power source 130 and host device 110. Inresponse to receiving this instruction, power limiting circuitry 121 mayalter the power path impedance.

In some embodiments, power limiting circuitry 121 may comprise a numberof different circuits operable to perform different functions. Forexample, turning to FIG. 2, FIG. 2 is a schematic of power limitingcircuitry according to an embodiment of the present invention. Inaccordance with an embodiment, power limiting circuitry 121 includesboth impedance altering circuitry 121 a and identification circuitry 121b. Impedance altering circuitry 121 a may be disposed in the power pathbetween power source 130 and host device 110, whereas identificationcircuitry 121 b may be disposed between impedance altering circuitry 121a and data pin 124.

Identification circuitry 121 b, which may be implemented at leastpartially in hardware or software as a processor or other type of logic,may be operable to receive power and data from host device 110 via datapin 124 and respond to the received data. For example, identificationcircuitry 121 b may have stored therein an accessory identifier, and maybe operable to communicate the accessory identifier to host device 110in response to receiving a request for the accessory identifier.Identification circuitry 121 b may also be operable to send instructionsto impedance altering circuitry 121 a instructing impedance alteringcircuitry 121 a to alter an impedance of the power path between powersource 130 and host device 110.

Impedance altering circuitry 121 a, which may be implemented at leastpartially in hardware or software as a processor or other type of logic,may be operable to alter an impedance of the power path between powersource 130 and host device 110. This may be in response to aninstruction from identification circuitry 121 b or, in some embodiments,in response to an instruction sent directly from host device 110. Thereare various ways that impedance altering circuitry 121 a may alter theimpedance of the power path, as further described herein.

Turning to FIG. 3, FIG. 3 is a schematic of impedance altering circuitry121 a according to one embodiment of the present invention. Impedancealtering circuitry 121 a according to this embodiment includes aresistive element 2 coupled in parallel with a switch 4 where both arearranged in a power path between points A and B. Resistive element 2 mayprovide any suitable resistance for measurably altering an impedancecharacteristic of power limiting circuitry 121 a. For example, resistiveelement 600 may have a resistance of 1 Ohm, 2

Ohm's, 3 Ohm's, 100 Ohm's, 200 Ohm's, 300 Ohm's, 1 kOhm, 2 kOhm's, 3kOhm's, 1 MOhm, 2 MOhm's, 3 MOhm's, be in a range from 1 to 3 Ohm's, 100Ohm's to 300 Ohm's, 1 kOhm to 3 kOhm, 1 MOhm to 3 MOhm's, or less than 1Ohm or greater than 3 MOhm's. Resistive element 2 includes a first end 5that may be coupled to power source 130, and a second end 6 that may becoupled to power pin 123 of connector 122, such that resistive element 2is disposed in a power path between power source 130 and host device110.

Switch 4 may be any suitable switching element that allows currentprovided from power source 130 to selectively bypass resistive element2. For example, switch 4 may be a MOSFET, JFET, or other type oftransistor or other semiconductor device operable to switch electronicsignals and power. Switch 4 is coupled in parallel to resistive element2 and includes a first terminal 7 (e.g., a source) coupled to first end5 of resistive element 2, a second terminal 8 (e.g., a drain) coupled tosecond end 6 of resistive element 2, and a third terminal 9 (e.g., agate) for controlling the operation of switch 4. In some embodiments,first terminal 7 is coupled to power source 130, second terminal 8 iscoupled to power pin 123, and third terminal 9 is coupled to data pin124 of connector 122. Switch 4, when in an OFF state, has a resistancesignificantly higher than the resistance of resistive element 2. When inan ON state, switch 4 has a resistance that is significantly lower thanthe resistance of resistive element 2.

As mentioned, power limiting circuitry 121 (e.g., impedance alteringcircuitry 121 a) may operate to alter an impedance of a power pathbetween power source 130 and host device 110. In some embodiments, powerlimiting circuitry 121 may operate in different modes, such as in abypass mode and a power limiting mode. Such modes may be entered inresponse to instructions from host device 110 and, in some embodiments,power limiting circuitry 121 may operate in some modes (e.g., the powerlimiting mode) by default. Operating by default in power limiting modemay advantageously reduce user risk to exposed voltage potentials, suchas when connector 122 of accessory 120 is not connected to connector 112of host device 110.

Turning briefly to FIG. 4, FIG. 4 is a graph illustrating avoltage/current characteristic 200 of power limiting circuitry 121(e.g., impedance altering circuitry 121 a) operating in a bypass modeaccording to an embodiment of the present invention. While operating inthe bypass mode, impedance altering circuitry 121 a may operate to allowcurrent and voltage to pass through impedance altering circuitry 121 asubstantially unaltered. Accordingly, any current and voltage suppliedto impedance altering circuitry 121 a from power source 130 willsimilarly be supplied to host device 110. For example, power source 130may supply 5V to impedance altering circuitry 121 a. In the bypass mode,impedance altering circuitry 121 a may provide the 5V to power pin 123of connector 122. In some embodiments, a perfect bypass may be notachieved, and thus impedance altering circuitry 121 a may have a nominalaffect on the power passing therethrough while in bypass mode such ascausing a small voltage drop (e.g., a drop of 0.5V, 0.25V, or 0.1V, orin a range from 0.1V to 0.5V, or greater than 0.5V, or less than 0.1V,reduction in current, change in phase, etc.

In one embodiment, the bypass mode may result from switch 4 (FIG. 3)being operated in an ON state. As a result of the relatively lowresistance of switch 4 as compared to resistive element 2, currentprovided from power source 130 may pass through impedance alteringcircuitry 121 a substantially unaltered. Accordingly, a voltage at pointA will be substantially similar to that supplied at point B even as anincreased amount of current passes through impedance altering circuitry121 a.

Power limiting circuitry 121 (e.g., impedance altering circuitry 121 a)may also operate in a power limiting mode. Turning briefly to FIG. 5A,FIG. 5A is a graph illustrating a voltage/current characteristic 300 ofpower limiting circuitry 121 (e.g., impedance altering circuitry 121 a)operating in a power limiting mode according to a first embodiment ofthe present invention. While in the power limiting mode of operation,impedance altering circuitry 121 a may operate to limit an amount ofpower passed therethrough from power source 130 to host device 110. Forexample, impedance altering circuitry 121 a may limit the amount ofvoltage provided to host device 110 and, in some cases, impose greaterlimits on the amount of voltage provided to host device 110 in responseto an increasing amount of current being drawn through current limitingcircuitry 321.

In one embodiment, this voltage/current characteristic of impedancealtering circuitry 121 a for the power limiting mode may be achieved byplacing switch 4 (FIG. 3) into an OFF state. As a result of therelatively high resistance of switch 4 as compared to resistive element2, current provided from power source 130 may pass through resistiveelement 2. Since resistive element 2 has a resistance that is greaterthan a nominal amount such as 0 Ohms, a voltage at point A will decreasecompared to that supplied at point B as an increased amount of currentpasses through impedance altering circuitry 121 a.

It should be recognized that a power limiting mode is not limited to thevoltage/current characteristic discussed with reference to FIG. 5A. Forexample, FIG. 5B is a graph illustrating a voltage/currentcharacteristic 310 of power limiting circuitry 121 (e.g., impedancealtering circuitry 121 a) operating in a power limiting mode accordingto a second embodiment of the present invention. In accordance with thisembodiment, while operating in the power limiting mode, impedancealtering circuitry 121 a may operate to reduce a voltage provided bypower source 130 if a certain amount of current is drawn throughimpedance altering circuitry 121 a. For example, the voltage may bereduced by a certain amount, such as 1V, 2V, or 3V, in a range from 1Vto 3V, by an amount less than 1V or greater than 3V, or the voltage maybe reduced to a certain voltage (e.g., 0V, −1V, +1V, −2V, +2V, etc.). Inone embodiment and as illustrated in FIG. 5B, the voltage may be reducedto approximately 0V in the event that at least a threshold amount ofcurrent, I_threshold, is drawn through impedance altering circuitry 121a.

Switching between the bypass and power limiting modes of operation mayresult in a predictable change in one or more electrical characteristicsof accessory 120. For example, where power limiting circuitry 121 isoperable to switch between the bypass and power limiting modes ofoperation and at least an amount of current equal to or greater thanI_threshold (FIG. 5A or 5B) is drawn through power limiting circuitry121, host device 110 may operate to measure the changes in theelectrical characteristics of accessory 120 as a result of the modeswitching. In the event the changes in the electrical characteristicsresulting from the mode switching satisfy some predetermined threshold,host device 110 may determine that accessory 120 includes power limitingcircuitry 121 and may thus determine whether accessory 120 includesparticular circuitry.

In accordance with one embodiment, host device 110 may send aninstruction to accessory 120 to change operation modes from a bypassmode of operation to a power limiting mode of operation and, if hostdevice 110 detects that accessory 120 successfully changed modes asinstructed, host device 110 may determine that accessory 120 includespower limiting circuitry 121. In another embodiment, host device 110 mayforce an amount of current to be drawn from power limiting circuitry 121that is greater than or equal to I_threshold via, for example, a currentsink located in host device 110. If host device 110 detects thataccessory 120 has some electrical characteristic associated with thedrawn amount of current (e.g., 0 V), host device 110 may determine thataccessory 120 includes power limiting circuitry 121. In yet anotherembodiment, host device 110 may both send an instruction to accessory120 to change modes of operation and draw an amount of current frompower limiting circuitry 121 that is greater than or equal toI_threshold.

Turning our attention now to host device 110, control circuitry 111 mayinclude a number of components operable to perform the functionalitydiscussed herein with reference to host device 110. FIG. 6 is aschematic of control circuitry 111 in accordance with an embodiment ofthe present invention. In this embodiment, control circuitry 111includes a processor 10, a current sink 12 (which may or may not beincluded in processor 10), a charge control switch 20, power controlcircuitry 40, and a battery 50. Control charge control switch 20 toactivate and deactivate charging of battery 50 or other internalcircuitry from a power source 130 in response to commands from processor10, while power control circuitry 40 may operate to protect battery 50or other internal circuitry from excess voltages passed through chargecontrol switch 20.

Processor 10 may be any suitable computer processor operable to performthe functions described herein, where processor 10 may be operable toperform various functions discussed with reference to control circuitry111 such as measuring voltages, comparing voltages, sending instructionsand receiving responses thereto, etc. Charge control switch 20 may be aMOSFET, JFET, or other type of transistor or other semiconductor deviceoperable to switch electronic signals and power. Charge control switch20 includes a first terminal 21 (e.g., a source) coupled to current sink12 and power pin 113, a second terminal 22 (e.g., a drain) coupled topower control circuitry 40, and a third terminal 23 (e.g., a gate)coupled to processor 10. Processor 10 may be operable to change a stateof charge control switch 20 via third terminal 23, such as by placingcharge control switch 20 into an ON state or an OFF state. When in theON state, charge control switch 20 may be operable to connect powercontrol circuitry 40 to power pin 113 (FIG. 1), and when in the OFFstate, charge control switch 20 may be operable to disconnect powercontrol circuitry 40 from power pin 113. Accordingly, processor 10 mayoperate to activate or deactivate charging of battery 50 or otherinternal circuitry from power source 130 by enabling or disabling chargecontrol switch 20. In some embodiments, power control circuitry 40 maybe operable to prevent excess voltage from power source 130 from beingprovided to battery 50 or other internal circuitry.

Turning briefly to FIG. 7, FIG. 7 is a schematic of power controlcircuitry 40 in accordance with an embodiment of the present invention.Power control circuitry 40 includes an overvoltage protection switch 42and a processor 44. Overvoltage protection switch 42 may be a MOSFET,JFET, or other type of transistor or other semiconductor device operableto switch electronic signals and power. Overvoltage protection switch 42includes a first terminal 42 a (e.g., a source) coupled to secondterminal 22 of charge control switch 20, a second terminal 42 b (e.g., adrain) coupled to other internal circuitry of host device 110 operableto store a charge provided via accessory 120 (e.g., battery 50), and athird terminal 42 c (e.g., a gate) coupled to processor 44.

Processor 44 may be operable to receive information indicating a voltageat first terminal 42 a of overvoltage protection switch 42. In someembodiments, processor 44 may include analog-to-digital functionalityoperable to convert an analog voltage read at first terminal 42 a to adigital value. Processor 44 may also be coupled to third terminal 42 cof overvoltage protection switch 42 and operable to change a state ofovervoltage protection switch 42 via third terminal 42 c, such as byplacing overvoltage protection switch 42 into an ON state or an OFFstate. When in the ON state, overvoltage protection switch 42 may beoperable to connect other circuitry that is internal to host device 110(e.g., battery 50) to second terminal 22 of charge control switch 20,and when in the OFF state, overvoltage protection switch 42 may beoperable to disconnect the other internal circuitry from second terminal22. In operation, processor 44 may place overvoltage protection switch42 into the OFF state when a voltage at first terminal 42 a exceeds apredetermined value, and otherwise place overvoltage protection switchinto the ON state.

Further, power control circuitry 40 (e.g., processor 44) may be coupledto processor 10 via a power line 30 that is operable to provide avoltage from power control circuitry 40 to processor 10 so as to powerprocessor 10. In some embodiments, power line 30 may be operable toprovide a voltage to processor 10 from an internal charge storageelement (e.g., battery 50) of host device 110 regardless of whether hostdevice 110 receives power from power source 130.

System 100 in certain embodiments may be a system for determiningwhether an accessory includes particular circuitry. However, it will beappreciated by those of ordinary skill in the art that such a systemcould operate equally well with more or, in some instances, fewercomponents than are illustrated in FIG. 1. Similarly, it will beappreciated by those of ordinary skill in the art that the schematicsillustrated in and discussed with reference to FIGS. 2, 3, 6, and 7could operate equally well with more or, in some cases, fewercomponents, and that the characteristics depicted in and discussed withreference to FIGS. 4 through 5B are merely example voltage/currentcharacteristics. Thus, the depictions in FIGS. 1 through 7 should betaken as being illustrative in nature, and not limiting to the scope ofthe disclosure.

FIG. 8A is a flowchart of a process 400 for operating a host device inaccordance with an embodiment of the present invention. Process 400 canbe performed by any suitable electronic device such as host device 110(FIG. 1), but is equally applicable to other electronic devicesdescribed herein.

At block 410, the host device (e.g., host device 110) establishes aconnection with an accessory (e.g., accessory 120). In establishing aconnection with the accessory, the host device and the accessory mayinitially be physically coupled to one another. For example, connector112 may mate with connector 122. In some embodiments, the host deviceand accessory may not physically couple to one another, but maywirelessly couple to one another. For example, each device may includewireless circuitry operable to communicate over wireless networks (e.g.,WLAN, IEEE 802.11, etc.), wireless sensor networks (e.g., Bluetooth,Zigbee, etc.), short-range point-to-point communication link (e.g.,IrDA, RFID, NFC, etc.).

In some embodiments, establishing a connection may include the hostdevice providing power to the accessory. For example, host device 110may provide power to accessory 120 over the same data pin used tocommunicate with accessory 120, where such power may be providedsimultaneously with communicating with accessory 120. This may be doneto provide accessory 120 with operating power in the event accessory 120does not have a power source or does not acquire operating power from apower source remote from accessory 120.

In at least one embodiment, establishing a connection with the accessoryincludes detecting a mechanical connection with the accessory. Forexample, the host device may monitor a pin in a connector of the hostdevice, such as power pin 113 and/or data pin 114, for a change ofimpedance, voltage, or other electrical characteristic. Some specifictechniques for detecting connection with an accessory are disclosed incommonly-owned and co-pending U.S. patent application Ser. No. ______(attorney docket number 90911-825181), titled “TECHNIQUES FORCONFIGURING CONTACTS OF A CONNECTOR”, filed on ______, the fulldisclosure of which is incorporated by reference herein in its entiretyfor all purposes. Once the mechanical connection is detected, the hostdevice may then continue to perform other handshaking operations, suchas those discussed with reference to FIG. 8C.

At block 420, the host device determines whether the accessory includesparticular circuitry (e.g., power limiting circuitry 121). Indetermining whether the accessory includes particular circuitry, thehost device may determine whether the accessory includes that particularphysical circuitry having certain characteristics and/or softwaremodules that perform the functionality of the power limiting circuitry.Some particular embodiments for determining whether the accessoryincludes particular circuitry are further discussed with reference toFIG. 8D.

If at block 420, the host device determines that the accessory includesthe particular circuitry (e.g., power limiting circuitry), the hostdevice performs action “A” at block 430. Action “A” may be one or moreof a variety of actions. For example, the host device may begin toaccept power from a power source via the accessory (by, e.g., closingcharge control switch 20 in FIG. 6, or otherwise coupling power pin 113to internal charge circuitry). For another example, in the event thehost device is already receiving power from the power source via theaccessory, the host device may continue to accept power from the powersource via the accessory. For yet another example, the host device maycommunicate information to the user of the host device (via, e.g., adisplay, audio, or other output unit of the device) or to anothercomputing device (via, e.g., a wired or wireless network connection)indicating that the accessory includes the particular circuitry orotherwise indicating that the accessory is authorized for use with thehost device. In some embodiments, one of more of these actions may beperformed simultaneously.

On the other hand, if at block 420 the host device determines that theaccessory does not include the particular circuitry, the host deviceperforms action “B” at block 440 which is different than action “A”.Action “B” may be one or more of a variety of actions. For example, thehost device may refuse to accept power from a power source via theaccessory (by, e.g., opening charge control switch 20 in FIG. 6, orotherwise decoupling power pin 113 from internal charge circuitry). Foranother example, in the event the host device is already receiving powerfrom the power source via the accessory, the host device may then stopaccepting power from the power source via the accessory. For yet anotherexample, the host device may communicate information to the user of thehost device (via, e.g., a display, audio, or other output unit of thedevice) or to another computing device (via, e.g., a wired or wirelessnetwork connection) indicating that the accessory does not include theparticular circuitry or otherwise indicating that the accessory is notauthorized for use with the host device. In some embodiments, one ofmore of these actions may be performed simultaneously.

Turning now to FIG. 8B, FIG. 8B is a flowchart of a process 410 for ahost device to establish a connection with an accessory according to afirst embodiment of the present invention. Process 410 can be performedby any suitable electronic device such as host device 110 (FIG. 1), butis equally applicable to other electronic devices and accessoriesdescribed herein. In accordance with some embodiments, process 410 mayfacilitate or assist in facilitating the establishment of acommunication link and/or a power path between a host device and anaccessory. This may include sending information from the host device tothe accessory on a data pin and, if no response or an unacceptableresponse is received, re-sending the information on the same data pin.In at least one embodiment, once an acceptable response is received fromthe accessory, the host device may begin charging or otherwise receivingpower provided from a power source via the accessory.

At block 411, the host device sends a request for an accessoryidentifier to the accessory. The request may be a request for theaccessory to send an identifier identifying the device. The accessoryidentifier may identify one or more suitable characteristics of theaccessory. For example, the accessory identifier may include a productname and/or number associated with the accessory, a name and/or numberidentifying the manufacturer of the accessory, a serial number or otheridentifier uniquely identifying a particular accessory, a MAC address,IP address, or other network-based identifier associated with theaccessory, etc. For another example, the accessory identifier mayidentify whether the accessory is operable to communicate using one ormore of a plurality of communication protocols, such as USB, UART, JTAG,etc., whether the accessory is operable to receive charging power fromthe host device, etc. In one particular example, the accessoryidentifier may include pin configuration information that instructs thehost device as to which function (e.g., receive charging/operatingpower, communicate using USB, communicate using ART, etc.) the hostdevice should implement for one or more of its pins of connector 112.Some accessory identifiers are described in the context of responsesequences for responding to a request for pin configuration andaccessory capability information in U.S. patent application Ser. No.______ (attorney docket number 90911-818777), titled “DATA STRUCTURESFOR FACILITATING COMMUNICATION BETWEEN A HOST DEVICE AND AN ACCESSORY”,filed ______, the entire contents of which are incorporated herein byreference in their entirety for all purposes.

In some embodiments, the request for an accessory identifier may includeinformation about the host device. For example, the request may includea host identifier, where the host identifier may identify one or moresuitable characteristics of the host. For example, like the accessoryidentifier, the host identifier may include a product name and/or numberassociated with the host device, a name and/or number identifying themanufacturer of the host device, a serial number or other identifieruniquely identifying a particular host device, a MAC address, IPaddress, or other network-based identifier associated with the hostdevice, etc.

In at least one embodiment, the request for an accessory identifier maybe communicated using one or more of a variety of error detection and,in some embodiments, error correction, techniques. Error detectiontechniques which may be used include the use of repetition codes, paritybits, checksums, cyclic redundancy checks (CRCs), cryptographic hashfunctions, error-correcting codes, etc. Accordingly, in someembodiments, the request for an accessory identifier includes errordetection information suitable for use in such errordetection/correction techniques. For example, the request may includeone or more parity bits, checksums, CRC check values, hash functionoutputs, etc. In some embodiments, the error detection information maybe sent separate from the request.

The request may be sent via any suitable mechanism. For example, withreference to FIG. 1, control circuitry 111 may generate and send therequest via a data pin such as data pin 114. The request may be sent toany suitable recipient. For example, again with reference to FIG. 1, thehost device may send the request to accessory 120. Further, the requestmay be sent at any suitable time. For example, the host device may beoperable to detect a mechanical, electrical, wireless, or otherconnection with the accessory and, in response to detecting such aconnection, send the request via the data pin.

At block 412, the host device monitors the data pin on which it sent therequest for an accessory identifier. For example, with reference to FIG.1, where host device 110 sends a request for an accessory identifier viadata pin 114, the host device may then monitor data pin 114. Monitoringmay be performed by a processor or other circuitry and/or software inthe host device, such as by control circuitry 111. In some embodiments,the host device may monitor other data pins or other communication means(e.g., wireless communication circuitry).

At block 413, the host device determines whether the requested accessoryidentifier is received. In some embodiments, the host device maydetermine whether the requested accessory identifier is received on thesame pin which the request was sent out on. For example, host device 110may determine whether the requested accessory identifier is received viadata pin 114. In other embodiments, the host device may determinewhether the request accessory identifier is received on a different pinor by some other communication means (e.g., wireless).

If at block 413 the host device determines that the requested accessoryidentifier is not received (e.g., due to a timeout), processing mayreturn to block 411 where another request for an accessory identifier issent. For example, one or more subsequent requests for accessoryidentifiers may be sent on data pin 114. In some embodiments, the hostdevice my stop sending requests after a certain number of requests havebeen sent, after a certain time period has elapsed, or in response tosome other condition being satisfied. In other embodiments, the hostdevice may continuously send such requests until a satisfactory responseis received.

If at block 413 the host device determines that the requested accessoryidentifier is received, processing may continue to block 415 where thehost device may read the accessory identifier. For example, withreference to FIG. 1, control circuitry 111 may read the accessoryidentifier received on data pin 114 or another data pin (not shown). Insome embodiments, the received accessory identifier may be stored by thehost device.

In some embodiments, the host device may use a timer when determiningwhether an accessory identifier has been received. If the timer hasexpired before an accessory identifier has been received, then the hostdevice may re-send the request. For example, the host device mayinitiate a timer after sending the request for an accessory identifieras discussed with reference to block 411. The determination as towhether an accessory identifier has been received, as discussed withreference to block 413, may then be made once the timer has expired. Thetimer may set to have any suitable duration. For example, the timer mayexpire after 1 ms, 2 ms, 3 ms, or at a time in the range of 1 ms to 3ms, or at a time less than 1 ms or greater than 3 ms.

At block 416 the host device determines whether the received accessoryidentifier is valid. Determining the validity of the received accessoryidentifier may include one or more of a variety of operations. In oneembodiment, the accessory identifier may be communicated using one ormore of a variety of error detection and, in some embodiments, errorcorrection, techniques, similar to those discussed above with referenceto the request for an accessory identifier. Accordingly, determining thevalidity of the received accessory identifier may include performingerror detection on the accessory identifier. In some embodiments, thismay include using error detection information, such as parity bits,checksums, CRC check values, hash function outputs, etc., communicatedwith or separate from the accessory identifier. In the event the hostdevice does not detect any errors in the received accessory identifier,the host device may determine that the received accessory identifier isvalid. In contrast, in the event the host device detects one or moreerrors in the received accessory identifier, the host device maydetermine that the received accessory identifier is not valid. In someembodiments, in the event the host device detects one or more errors inthe received accessory identifier, the host device may attempt tocorrect those errors and subsequently determine that the receivedaccessory identifier is not valid only if it is unable to correct atleast one of those errors.

In another embodiment, the received accessory identifier may be comparedto a list of authorized accessory identifiers. For example, the hostdevice may have stored therein, or be operable to access from a locationremote from the host device, a database including the list of authorizedaccessory identifiers, where the accessory identifiers provided on thelist have been authorized to operate with the host device. By comparingthe received accessory identifier to the list of authorized accessoryidentifiers, the host device may check to see if the received accessoryidentifier matches one or more of the accessory identifiers provided onthe list. In the event of a match, the host device may determine thatthe received accessory identifier is valid. In contrast, in the eventthe received accessory identifier does not match any of the accessoryidentifiers provided on the list, the host device may determine that thereceived accessory identifier is not valid.

In some embodiments, the accessory identifier may also include controlinformation. The control information may provide one or more parametersto configure the host device to communicate or provide power to theaccessory. For example, the control information may instruct the hostdevice to configure itself for USB, UART, or other types ofcommunication with the accessory. In one embodiment and with referenceto FIG. 1, connector 112 may include additional pins for communicatingwith accessory 120 or an electronic device other than accessory 120,such as additional data pins 115. Additional data pins 115 may each beselectively configured to communicate over a number of differentcommunication protocols, such as USB, UART, JTAG, etc. The controlinformation may then instruct the host device to use a particularcommunication protocol (e.g., one of USB, UART, JTAG, etc.) tocommunicate over a particular pin (e.g., one of additional data pins115). As a result, control circuitry 111 may subsequently communicatedata to components of accessory 120 (which may include power limitingcircuitry 121 or be separate from power limiting circuitry 121) using acommunication protocol selected by the accessory 120 over a particularpin selected by accessory 120.

If the host device determines that the received accessory identifier isnot valid, processing may return to block 411, where the host device maysend another request for an accessory identifier as previouslydescribed. In contrast, if the host device determines that the receivedaccessory identifier is valid, processing may continue with block 417.

At block 417, the host device at least temporarily receives power fromthe power source via the accessory. For example, with reference to FIG.1, host device 110 may receive power from power source 130 via accessory120. In one embodiment, host device 110 may receive power from powersource 130 that is communicated to power pin 123 of accessory 120 viapower limiting circuitry 121, where host device 110 receives the powerby power pin 113 of host device 110. For example, in one embodiment,processor 10 (FIG. 6) may communicate a signal to third terminal 23(FIG. 6) to place charge control switch 20 (FIG. 3) into an ON statesuch that power from power pin 113 may be communicated to chargecircuitry or other internal circuitry of host device 110.

In one embodiment, as a result of placing charge control switch 20 intoan ON state, power from power pin 113 may be communicated to powercontrol circuitry 40 (FIG. 6). Power control circuitry 40 may thenoperate to communicate the power to other circuitry of the host device110 (e.g., battery 50) if the power is less than some predeterminedmaximum. For example, if the voltage at first terminal 42 a (FIG. 7) isless than or equal to a predetermined maximum voltage.

The power received by the host device may be used in any suitablefashion. For example, the host device may use the received power tooperate internal circuitry of the host device, and/or to charge aninternal battery (e.g., battery 50) of the host device. In this fashion,the host device may only charge and/or operate with accessoriesproviding a valid accessory identifier. It should be recognized,however, that the power received by the host device at this point mayonly be temporarily accepted and used by the host device. With referenceto FIG. 8A, processing then continues to block 420, where the hostdevice may then determine whether the accessory includes power limitingcircuitry. In some embodiments, if it is determined that the accessorydoes not include power limiting circuitry, the host device may stopaccepting power received from the accessory. Accordingly, the powerreceived at block 417 may only be temporarily accepted or otherwise usedby the host device.

FIG. 8C is a flowchart of a process 410 for a host device to establish aconnection with an accessory according to a second embodiment of thepresent invention. The operations illustrated in the process of FIG. 8Care the same as those illustrated and discussed with reference to FIG.8B, where blocks 411A to 417A are substantially the same as therespectively numbered blocks 411 to 417. However, in this embodiment,the host device may switch data pins and send subsequent requests for anaccessory identifier on a different data pin. Such a process may beparticularly advantageously in embodiments where the connectors aremulti-orientation connectors, whereby they may mate together in multipleorientations. However, such a process may also be used in embodimentswhere the connectors are single-orientation connectors.

As mentioned, blocks 411A to 417A depicted in FIG. 8C are substantiallythe same as the corresponding blocks 411 to 417 depicted in FIG. 8B, andthus further description is omitted. In this embodiment, however, atblock 413A, in response to the host device determining that therequested identifier is not received, processing continues to block414A. Similarly, at block 416A, in response to the host devicedetermining that the received accessory identifier is not valid,processing continues to block 414A.

At block 414A, the host device switches data pins from the data pin bywhich the request for an accessory identifier was communicated to adifferent data pin. For example, with reference to FIG. 1, where hostdevice 110 initially sends a request for an accessory identifier viadata pin 114, in the event that the host device determines that therequested accessory identifier is not subsequently received, the hostdevice may then switch data pins from data pin 114 to another data pin(e.g., one of additional data pins 115) provided in connector 112. Uponswitching from data pin 114 to another data pin, processing may thenreturn to block 411A, where the host device sends the request for anaccessory identifier on the other data pin rather than data pin 114.

In some embodiments, when switching between data pins, the host devicemay cycle through available pins in any suitable sequence. In someembodiments, the host device may include more than two data pins. Thehost device may then use all or a subset of those pins to communicaterequests for accessory identifiers. For example, the host device maycycle through all of the pins and communicate the request on all of thepins, or the host device may cycle through only a subset of the pins andcommunicate the request on only the subset of pins. Upon communicatingthe request on all or only the subset of pins, the host device may thenagain communicate the request on all or only the subset of pins. Thehost device may continue to send requests until a satisfactory responseis received. In some embodiments, the host device may include only twodata pins. In such a case, the host device may alternate between the twodata pins such that requests are communicated on each of the pins in acyclical manner.

In some embodiments and as described with reference to FIG. 8C, the hostdevice may use a timer when determining whether an accessory identifierhas been received at block 413A. In this case, if the timer has expiredbefore an accessory identifier has been received, then processing maycontinue to block 414A, where the host device may switch data pins andthen re-send the request.

Turning now to FIG. 8D, FIG. 8D is a flowchart of a process 420 fordetermining whether an accessory includes particular circuitry (e.g.,power limiting circuitry) according to some embodiments of the presentinvention. Process 420 can be performed by any suitable electronicdevice such as host device 110 (FIG. 1), but is equally applicable toother electronic devices and accessories described herein. In accordancewith some embodiments, process 420 may facilitate or assist infacilitating the establishment or maintenance of a power path between ahost device and an accessory. This may include sending instructions fromthe host device to the accessory, and/or sinking current from the powersource via the accessory. Electrical characteristics of the accessory(e.g., a voltage received from the accessory) may be measured before andafter such operations are performed, and those electricalcharacteristics may be compared with one another to determine whetherthe accessory includes the particular circuitry.

At block 421, a host device (e.g., host device 110 of FIG. 1) measures afirst electrical characteristic of an accessory, such as a first voltagereceived from an accessory (e.g., accessory 120 of FIG. 1). For example,the host device may measure a voltage provided at a power pin of aconnector of the host device (e.g., power pin 113). The voltage measuredat the power pin may, by way of connection to the accessory, correspondto a voltage provided by a power source (e.g., power source 130) subjectto alteration by power limiting circuitry (e.g., power limitingcircuitry 121). According to one embodiment, the power limitingcircuitry may by default operate in a bypass mode such as that discussedwith reference to FIG. 4. Accordingly, the first voltage may berelatively high, such as that shown in the voltage/currentcharacteristic illustrated in FIG. 4.

At block 422, the host device sends an instruction to the accessory toalter an impedance (or other electrical characteristic of theaccessory), at the accessory, of a power path between a power source(e.g., power source 130) and a host device (e.g., host device 110). Forexample, host device 110 may communicate an instruction via data pin 114to power limiting circuitry 121. The instruction may instruct the powerlimiting circuitry to switch between modes of operation, such asswitching from a bypass mode (such as that discussed with reference toFIG. 4) to a power limiting mode (such as one of those discussed withreference to FIGS. 5A and 5B). In one particular embodiment, theinstruction may be communicated to identification circuitry 121 b which,after determining that the instruction is valid, instructs the impedancealtering circuitry 121 a to alter the impedance of the power path. To doso, identification circuitry 121 b may control third terminal 9 so as tochange switch 4 between an ON state and an OFF state. By changing animpedance of power limiting circuitry 121, an impedance of the powerpath between power source 130 and host device 110 may effectively bealtered.

At block 423, the host device sinks current from the power source viathe accessory. For example, host device 110 may include a current sink12 (FIG. 6) coupled to power pin 113, which sinks current from powersource 130 via power pin 113 of host device 110, power pin 123 ofaccessory 120, and power limiting circuitry 121. By sinking current fromthe power source, the host device may force the power limiting circuitryto operate in a particular mode or in a particular region with referenceto its operating characteristics. For example, with reference to FIG.5B, the host device may draw an amount of current through the powerlimiting circuitry greater than 1 threshold so as to cause the powerlimiting circuitry to reduce a voltage provided at a power pin (e.g.,power pin 123) to approximately 0 V. For another example, with referenceto FIG. 5A, the host device may draw an amount of current through thepower limiting circuitry greater than I_threshold so as to cause thepower limiting circuitry to provide a voltage at a power pin (e.g.,power pin 123) that is less than or equal to V_limit.

By both drawing current from the power source via the accessory andsending the instruction to the accessory to alter its impedance, theaccessory is effectively forced to operate in a particular operatingmode and at a particular operating region. For example, with referenceto FIGS. 4, 5A, and 5B, the instruction to enter into a power limitingmode should ensure that the accessory has voltage/currentcharacteristics such as one of those shown in either FIG. 5A or 5B.Then, by forcing an amount of current through the accessory that is atleast equal to I_threshold, the voltage output by the accessory shouldbe forced to be approximately V_limit or 0V. Accordingly, by providingsuch an instruction and forcing such an amount of current through theaccessory, the host device can determine whether the accessory includesnot only the circuitry necessary to interpret the instruction sent fromthe host device but also the circuitry necessary to change an impedanceof the power path between the power source and the host device.

At block 424, the host device measures a second voltage received fromthe accessory. The second voltage measurement may be made in a mannersimilar to that of the first voltage measurement. For example, hostdevice 110 may again measure a voltage provided at power pin 113.

At block 425, the host device determines whether the accessory includesthe particular circuitry (e.g., power limiting circuitry 121) based onthe relationship between the first voltage (or other electricalcharacteristic) measured at block 421 and the second voltage (or otherelectrical characteristic) measured at block 424. In one embodiment, thehost device does this by determining whether the first voltage isgreater than the second voltage. If it is determined that the firstvoltage is greater than the second voltage, then processing continues toblock 426 where the host device determines that the accessory includesthe particular circuitry. If it is determined that the first voltage isnot greater than the second voltage, then processing continues to block427 where the host device determines that the accessory does not includethe particular circuitry.

For example, with reference to FIG. 4, the first voltage may be measuredwhile power limiting circuitry 121 operates in bypass mode and is thusrelatively high. Turning to FIGS. 5A and 5B, the second voltage may thenbe measured to be relatively low as long as an amount of current equalto or greater than I_threshold is drawn through power limiting circuitry121. By measuring a difference in voltage, and/or by determining thatthe second voltage is approximately equal to some value (e.g., V_limitor 0V), host device 110 may determine that accessory 120 includes powerlimiting circuitry 121. In some embodiments, block 423, that is thesinking of current by the host device from the power source, may ensurethat at least an amount of current equal to I_threshold is drawn throughthe power limiting circuitry. In other embodiments, such a current sinkmay be excluded as the power source may provide such current in anyevent.

It should be apparent that accessories without power limiting circuitrymay not change an electrical characteristic in response to one or moreof the operations performed at blocks 422 and 423. For example, anaccessory that does not include power limiting circuitry may pass powerfrom the power source to the host device unaltered, as shown in FIG. 4.In such cases, both a first and second measured voltage would beapproximately the same, and thus the host device may determine that theaccessory does not include the power limiting circuitry.

It should also be recognized that embodiments of the invention are notlimited to measuring and comparing voltages received from an accessory.Rather, other electrical characteristics of the accessory and/or a powerpath between a power source and a host device via the accessory may bemeasured and compared. For example, the host device may measure andcompare impedances, voltages, currents, voltage/current magnitudes,voltage/current phases, etc.

Further, one of ordinary skill would recognize that embodiments may notbe limited to determining whether the first voltage is greater than thesecond voltage as discussed with reference to block 425, but in somecases at block 425 the host device may alternatively determine whetherthe first voltage is less than the second voltage and, if so, concludethat the accessory includes power limiting circuitry. For example, priorto measuring the first voltage, current may be sinked from the powersource. Then, after measuring the first voltage, the current sink may beremoved, and the second voltage measured thereafter. For anotherexample, at block 422, instead of instructing the accessory to switchfrom a bypass mode to a power limiting mode, the host device mayinstruct the accessory to switch from a power limiting mode to a bypassmode.

It should be appreciated that the specific operations illustrated inFIGS. 8A to 8D provide particular methods that may be executed by a hostdevice, according to certain embodiments of the present invention. Whilethe operations illustrated in FIGS. 8A to 8D are often discussed withreference to FIG. 1, it should be appreciated that the operations may beperformed by other types of host devices and accessories. Further, othersequences of operations may also be performed according to alternativeembodiments. For example, alternative embodiments of the presentinvention may perform the operations outlined above in a differentorder. Moreover, the individual operations illustrated in FIGS. 8A to 8Dmay include multiple sub-operations that may be performed in varioussequences as appropriate to the individual operations.

Further, additional operations may be added depending on the particularapplications. For example, before block 421 of measuring a first voltagereceived from the accessory, the host device may communicate aninstruction to the accessory to operate in a particular mode ofoperation, such as a bypass mode. Moreover, existing operations may beremoved depending on the particular applications. For example, block 422or block 423 may be omitted. Where block 422 is omitted, the currentsink may force the power limiting circuitry to operate in differentregions of a mode of operation, where the different regions havemeasurable differences in electrical characteristics. Where block 423 isomitted, the instruction from the host device to the accessory may causethe power limiting circuitry to operate in different modes of operationhaving measurable differences in electrical characteristics. Further,one of ordinary skill in the art would readily recognize that the powerlimiting circuitry may operate to alter not only a voltage provided at apower pin (e.g., power pin 123) as discussed above, but could similarlyalter other electrical characteristics of the accessory and/or the powerpath provided between the power source and the host device.

As mentioned, various functionality of the host device may beimplemented in hardware, software, or a combination thereof. In oneparticular embodiment, the functionality of the host device thatoperates the processes depicted in and discussed with reference to FIGS.8B and 8C may be implemented in hardware, whereas that of FIG. 8D may beimplemented in software. In such an embodiment, the hardware circuitrythat performs the operations discussed with reference to FIGS. 8B and 8Cmay be operable to execute using no or only a very small amount ofpower. As a result of these operations being performed, the host devicemay then, at least temporarily, receive power from the accessory. Oncethe host device begins to receive full operating power via theaccessory, the host device may boot up its operating system, andsubsequently perform the operations discussed with reference to FIG. 8Dfor determining whether or not to continue receiving power via theaccessory.

FIG. 9A is a flowchart of a process 500 for operating an accessory, suchas accessory 120, according to an embodiment of the present invention.Process 500 can be performed by any suitable electronic device such asaccessory 120 (FIG. 1), but is equally applicable to other accessoriesdescribed herein.

At block 510, the accessory (e.g., accessory 120) establishes aconnection with a host device (e.g., host device 110). In establishing aconnection with the host device, the accessory and the host device mayengage in a handshaking protocol so as to facilitate communicationbetween the devices. In some embodiments, establishing a connection mayinclude the accessory receiving power from the host device, and in somecases, may also or alternatively include the accessory communicatingpower to the host device from a power source. Some particularembodiments for establishing a connection with a host device arediscussed with reference to FIG. 9B.

At block 520, the accessory (e.g., accessory 120) responds toinstructions provided by the host device (e.g., host device 110). Inresponding to instructions, the accessory may communicate informationback to the host device and/or, in some embodiments, may alter a powerpath between a power source and the host device. Some particularembodiments for responding to instructions provided by the host deviceare discussed with reference to FIG. 9C.

Turning now to FIG. 9B, FIG. 9B is a flowchart of a process for anaccessory (e.g., accessory 120) to establish a connection with a hostdevice (e.g., host device 110) according to some embodiments of thepresent invention. At block 511, the accessory monitors a data pin ofthe accessory. For example, with reference to FIG. 1, accessory 120 maymonitor data pin 124. Monitoring may be performed by a processor orother circuitry and/or software in the accessory, such as by powerlimiting circuitry 121. In monitoring the data pin, the accessory maymonitor the data pin for information received from the host device, suchas a power signal and/or a request for an accessory identifier. Forexample, in one embodiment, identification circuitry 121 b (FIG. 2) maymonitor data pin 124 for changes in logic levels.

At block 512, the accessory determines whether it received power fromthe host device. In some embodiments, the accessory may receive powerfrom the host device. The accessory may receive any suitable amount ofpower, such as an amount of power sufficient for the accessory tooperate at least for a certain period of time. The power may becommunicated from the host device to the accessory using one or moretechniques. For example, the host device may wirelessly communicatepower to the accessory using electromagnetic induction, electromagneticradiation, electrical conduction, etc. In some embodiments, the powermay be communicated from the host device to the accessory by wire. Forexample, with reference to FIG. 1, host device 110 may communicate powerto accessory 120 via a pin of connector 122. The line which the hostdevice communicates power to the accessory may be the same or differentthan a line which the host device uses to communicate information to theaccessory. For example, with reference to FIG. 1, host device 110 maycommunicate both power and information to accessory via data pin 114.For another example, host device 110 may communicate information toaccessory 120 via data pin 114, and power to accessory 120 via a pinother than data pin 114. In at least one embodiment, host device 110 maycommunicate power to accessory 120 by maintaining the voltage at a datapin at a high state. Upon connecting host device 110 to accessory 120,identification circuitry 121 b or other internal circuitry may thendetermine that power is received from the host by identifying a highvoltage level at data pin 124.

In the event the accessory does not detect any received power from thehost device, the accessory may continue to monitor the data pin asdiscussed with reference to block 511. In contrast, in the event theaccessory detects power received from the host device, processing maycontinue with block 513.

At block 513, the accessory disables a power path between a power sourceand the host device. For example, with reference to FIG. 1, accessory120 may disable a power path from power source 130 to host device 110.The accessory may disable the power path using one or more of a varietyof techniques. In one embodiment, the accessory may increase animpedance of the power path between the power source and the hostdevice. For example, with reference to FIG. 1, power limiting circuitry121 may increase an impedance of the power path between power source 130and host device 110.

In some embodiments, power limiting circuitry 121 includesidentification circuitry 121 b and impedance altering circuitry 121 a asdiscussed with reference to FIG. 3, where the impedance alteringcircuitry 121 a may be operable in a bypass mode and a power limitingmode, as previously described. To disable the power path, identificationcircuitry 121 b may communicate an instruction to impedance alteringcircuitry 121 a to switch from the bypass mode to the power limitingmode.

At block 514, the accessory determines whether a request for anaccessory identifier is received. For example, with reference to FIG. 1,power limiting circuitry 121 may determine whether a request for anaccessory identifier is received via data pin 114. If the accessorydetermines that a request for an accessory identifier is not received,processing may continue with block 511, where the accessory continues tomonitor the data pin. If, on the other hand, the accessory determinesthat a request for an accessory identifier is received, processing maycontinue with block 515.

At block 515, the accessory reads the request for an accessoryidentifier. For example, with reference to FIG. 1, power limitingcircuitry 121 may read the request for an accessory identifier on datapin 124. In some embodiments, the received request may be stored by theaccessory.

At block 516, the accessory determines whether the request for anaccessory identifier is valid. Determining the validity of the receivedrequest may include one or more of a variety of operations. In oneembodiment, the request for an accessory identifier may be communicatedusing one or more of a variety of error detection and, in someembodiments, error correction, techniques, as described above withrespect to FIG. 8C. Accordingly, determining the validity of thereceived request may include performing error detection on the request.In some embodiments, this may include using error detection information,such as parity bits, checksums, CRC check values, hash function outputs,etc., communicated with or separate from the request. In the event theaccessory does not detect any errors in the received request, theaccessory may determine that the received request is valid. In contrast,in the event the accessory detects one or more errors in the receivedrequest, the accessory may determine that the received request is notvalid. In some embodiments, in the event the accessory detects one ormore errors in the received request, the accessory may attempt tocorrect those errors and subsequently determine that the receivedrequest is not valid only if it is unable to correct at least one ofthose errors.

In another embodiment, at least portions of the received request for anaccessory identifier may be compared to a list of authorized hostidentifiers. For example, the request for an accessory identifier mayinclude a host identifier as previously described with reference to FIG.8C. The accessory may have stored therein, or be operable to access froma location remote from the accessory, a database including the list ofauthorized host identifiers, where the host identifiers provided on thelist have been authorized to operate with the accessory. By comparingthe received host identifier included in the request (or in someembodiments, received separate from the request) to the list ofauthorized host identifiers, the accessory may check to see if thereceived host identifier matches one or more of the host identifiersprovided on the list. In the event of a match, the accessory maydetermine that the received request for an accessory identifier isvalid. In contrast, in the event the received host identifier does notmatch any of the host identifiers provided on the list, the accessorymay determine that the received request for an accessory identifier isnot valid.

If the accessory determines that the received request is not valid,processing may continue with block 511, where the accessory operates tomonitor the data pin. In contrast, if the accessory determines that thereceived request is valid, processing may continue with block 517.

At block 517, the accessory sends its accessory identifier to the hostdevice. For example, with reference to FIG. 1, accessory 120 may sendthe accessory identifier to host device 110 via data pin 124. In someembodiments, the accessory identifier may be stored in accessory 120. Inother embodiments, the accessory identifier may be acquired by accessory120 from a source remote from accessory 120.

At block 518, the accessory enables a power path between the powersource and the host device. For example, with reference to FIG. 1,accessory 120 enables the power path from power source 130 to hostdevice 110. The accessory may enable the power path using one or more ofa variety of techniques. In one embodiment, the accessory may decreasean impedance of the power path between the power source and the hostdevice. For example, with reference to FIG. 1, power limiting circuitry121 may decrease an impedance of the power path between power source 130and host device 110.

In some embodiments, power limiting circuitry 121 includesidentification circuitry 121 b and impedance altering circuitry 121 a asdiscussed with reference to FIG. 2, where the impedance alteringcircuitry 121 a may have be operable in a bypass mode and a powerlimiting mode, as previously described. To enable the power path,identification circuitry 121 b may communicate an instruction toimpedance altering circuitry 121 a to switch from the power limitingmode to the bypass mode.

The accessory enabling a power path at block 518 should be distinguishedfrom the host receiving power at block 417 (FIG. 8B) and receiving poweras performing action “A” at block 430 (FIG. 8A). The accessory mayprovide a voltage at a power pin of the host device, however whetherthat voltage is consumed or otherwise used by the host device is adifferent matter. The accessory enabling a power path refers to whetherthe accessory allows a voltage provided by a power source to passthrough to the host device substantially unaltered, or whether theaccessory suppresses, reduces, or otherwise alters that voltage. Incontrast, regardless of whether the accessory actually enables such apower path, the host device may decide whether or not to accept orotherwise consume power supplied to a power pin (or other pin). At block417, the host device may receive the power at least temporarily, forexample to charge the host device or provide the host device withsufficient power to operate in the event the host device does nototherwise have access to power sufficient to operate (e.g., it has adead battery). The host devices determination to receive supplied powermay then change based on a subsequent determination of whether theaccessory includes power limiting circuitry. If it does include suchcircuitry, the host device may then continue to receive the suppliedpower. Otherwise, it may then refuse to receive the supplied power.

Turning now to FIG. 9C, FIG. 9C is a flowchart of a process 520 for anaccessory to respond to instructions provided by a host device accordingto some embodiments of the present invention. Process 520 can beperformed by any suitable electronic device such as accessory 120 (FIG.1), but is equally applicable to other electronic devices andaccessories described herein. In accordance with some embodiments,process 520 may facilitate or assist in facilitating the establishmentof a power path between a host device and an accessory. This may includereceiving instructions from the host device and responding to thoseinstructions by altering an impedance of a power path between a powersource and the host device.

At block 521, the accessory (e.g., accessory 120) receives aninstruction from the host device (e.g., host device 110). For example,the power limiting circuitry (e.g., power limiting circuitry 121) in theaccessory may receive an instruction communicated from the host devicevia one or more data pins (e.g., data pin 114 and data pin 124). Theinstruction may be communicated using any suitable communicationprotocol.

At block 522, the accessory determines whether the instruction is aninstruction to alter a power path impedance, such as an impedance of apower path between the power source and the host device. If it isdetermined that the instruction is not an instruction to alter a powerpath impedance, processing may return to the beginning of operations sothat the accessory waits to receive another instruction from the hostdevice. If it is determined that the instruction is an instruction toalter a power path impedance, processing may continue with block 523.

In one embodiment and with reference to FIG. 3, the instruction may bean instruction to cause switch 4 to enter into either an ON state or anOFF state. For example, the instruction may cause switch 4 to enter intoan OFF state so that impedance altering circuitry 121 a (FIG. 2) has avoltage/current characteristic similar to that discussed with referenceto FIG. 5A. Alternatively, the instruction may cause switch 4 to enterinto an ON state so that impedance altering circuitry 121 a has avoltage/current characteristic similar to that discussed with referenceto FIG. 4.

At block 523, the power limiting circuitry alters an impedance, at theaccessory, of a power path between the power source and the host device.For example, with reference to FIG. 5B, in response to receiving aninstruction to enter a power limiting mode, accessory 120 may alter itsimpedance such that a voltage provided at power pin 123 is approximately0V when at least a threshold amount of current (I_threshold) is drawnthrough impedance altering circuitry 121 a. In another example, withreference to FIG. 5A, in response to receiving an instruction to enter apower limiting mode, accessory 120 may alter its impedance such that avoltage provided at power pin 123 is decreased compared to a voltageprovided by power source 130 with an increasing an amount of current. Inyet another example, in response to receiving an instruction to enterinto a bypass mode, accessory 120 may alter its impedance such that avoltage provided by power source 130 is approximately equal to a voltageprovided at power pin 123 for any given current such as that depicted inFIG. 4.

It should be appreciated that the specific operations illustrated inFIGS. 9A to 9C provide particular methods that may be executed by anaccessory, according to certain embodiments of the present invention.While the operations illustrated in FIGS. 9A to 9C are often discussedwith reference to FIG. 1, it should be appreciated that the operationsmay be performed by other host devices and accessories described herein.Further, other sequences of operations may also be performed accordingto alternative embodiments. For example, alternative embodiments of thepresent invention may perform the operations outlined above in adifferent order. Moreover, the individual operations illustrated inFIGS. 9A to 9C may include multiple sub-operations that may be performedin various sequences as appropriate to the individual operations.Furthermore, additional operations may be added or existing operationsremoved depending on the particular applications. One of ordinary skillin the art would recognize and appreciate many variations,modifications, and alternatives. For example, one of ordinary skill inthe art would readily recognize that power limiting circuitry 121 mayoperate to alter not only an impedance of a power path as discussedabove, but could similarly alter other electrical characteristics ofaccessory 120 and/or the power path provided between power source 130and host device 110.

FIG. 10A a system 600 for determining whether an accessory includesparticular circuitry according to a first embodiment of the presentinvention. According to this embodiment, system 600 includes a hostdevice 610 (e.g., host device 110 of FIG. 1), a computing system 620(e.g., power source 130 of FIG. 1), and an accessory 630 (e.g.,accessory 120 of FIG. 1). Host device 610 is electrically coupleable tocomputing system 620 via accessory 630.

Host device 610 may be any suitable electronic device that is operableto determine whether accessory 630 includes particular circuitry, andmay include one or more hardware and or software components operable tofacilitate determining whether accessory 630 includes particularcircuitry. For example, host device 610 may be a mobile phone, apersonal digital assistant (PDA), a handheld or portable device (e.g.,iPhone™, Blackberry™, etc.), a notebook, a personal computer, a notepad, a tablet computer, a media player (e.g., a music player or videoplayer), a camera, a game player, a laptop computer, a netbook, abooklet, or other electronic device configured for wired or wirelesscommunication. Host device 610 may include any suitable componentstypically found in such electronic devices necessary to perform theoperations discussed herein. For example, host device 610 may include auser interface 611 that may be operable to display information to theuser or receive inputs from the user (e.g., a touchscreen), a speaker612 for providing an audio output to a user, a microphone 613 forreceiving audio inputs from a user, one or more buttons 614 forcontrolling the operation of host device 610 via a user input, aconnector 615 such as a plug connector or a receptacle connector formechanically and electrically coupling host device 610 to otherelectronic components such as accessory 630, where connector 615 mayinclude one or more pins or conductive contacts for establishingelectrical and/or optical communication with corresponding pins orcontacts of a connector coupled to connector 615. Host device 610 mayalso include other suitable components typically found in such systemsfor performing the operations discussed herein, such as a processor (notshown), a tangible non-transitory computer readable storage medium (notshown), and the like, all operably coupled to one another such that theprocessor may execute instructions stored on the computer readablestorage medium so as to cause host device 610 to perform one or more ofthe operations discussed herein.

Accessory 630 may be any suitable electronic element operable toestablish a power path between host device 610 and a power source (suchas one provided in computing system 620, one provided via a power socketin a wall, one provided as a battery, etc.), and/or operable toestablish a communication path between host device 610 and anotherelectronic computing device such as computing system 620.

Accessory 630 according to this embodiment is a cable that includes oneor more conductive wires disposed therein, where the wires may beindividually insulated and, in some embodiments, the group of conductivewires may be bundled by an insulating sheath. The wires of accessory 630may be operable to carry voltage and current between host device 610 andother devices and/or power supplies, such as computing system 620. Insome embodiments, accessory 630 may additionally or alternativelyinclude optical conductors such as optical fibers operable tocommunicate light or other electromagnetic waves between host device 610and computing system 620.

Accessory 630 may include a first connector 631 which may be anysuitable connector, such as a plug connector or a receptacle connector,that includes one or more pins or conductive contacts for mechanically,electrically, and/or optically coupling the wires and/or opticalconductors of accessory 630 to host device 610 so as to establish apower path and/or a communication path between host device 610 and otherdevices and/or power sources, such as computing system 620. For example,first connector 631 may be a 30-pin connector such as that described inU.S. Pat. No. 6,776,660, which is incorporated herein by reference inits entirety for all purposes, a dual-orientation connector such as anyof those described in U.S. Provisional Patent Application No.61/556,692, filed Nov. 7, 2011, U.S. Provisional Patent Application No.61/565,372, filed Nov. 30, 2011, U.S. patent application Ser. No. ______(attorney docket number 90911-844750), titled “DUAL ORIENTATIONELECTRONIC CONNECTOR”, filed ______, and U.S. patent application Ser.No. ______ (attorney docket number 90911-832033), titled “CONNECTORS FORELECTRONIC DEVICES”, filed ______, all of which are incorporated hereinby reference in their entirety for all purposes, an RS232 serialconnector, a USB connector, an S-video connector, a VGA connector, anSDI connector, etc. First connector 631 may be sized and shaped tomechanically engage with connector 615 of host device 610, and connector615 of host device 610 may be sized and shaped to mechanically engagewith first connector 631.

Accessory 630 may also include a second connector 632 which may be anysuitable connector, such as a plug connector or a receptacle connector,that includes one or more pins or conductive contacts for mechanically,electrically, and/or optically coupling the wires and/or opticalconductors of accessory 630 to computing system 620 so as to establish apower path and/or a communication path between computing system 620 andhost device 610. For example, second connector 632 may be a 30-pinconnector such as that described in U.S. Pat. No. 6,776,660, adual-orientation connector such as any of those described in U.S.Provisional Patent Application No. 61/556,692, filed Nov. 7, 2011, U.S.Provisional Patent Application No. 61/565,372, filed Nov. 30, 2011, U.S.patent application Ser. No. ______ (attorney docket number90911-844750), titled “DUAL ORIENTATION ELECTRONIC CONNECTOR”, filed______, and U.S. patent application Ser. No. ______ (attorney docketnumber 90911-832033), titled “CONNECTORS FOR ELECTRONIC DEVICES”, filed______, all of which are incorporated herein by reference in theirentirety for all purposes, an RS232 serial connector, a USB connector,an S-video connector, a VGA connector, an SDI connector, etc. Secondconnector 632 may be the same or different than first connector 631.

Accessory 630 may further include power path control circuitry 633(e.g., power limiting circuitry 121) which may be any suitable hardwareand/or software for controlling a power path and/or communication pathbetween first connector 631 and second connector 632. Since power pathcontrol circuitry 633 is operable to control a power path and/orcommunication path between first connector 631 and second connector 632,power path control circuitry 633 may also be operable to control a powerpath and/or communication path between devices that may be mechanically,electrically, and/or optically coupled to the connectors of accessory630, such as host device 610 and computing system 620. Power pathcontrol circuitry 633 may control the power path between host device 610and computing system 620 in any one or more of a number of fashions. Forexample, power path control circuitry 633 may be operable to selectivelyalter a characteristic of the power path, such as an electricalimpedance, a voltage capacity, a current capacity, and the like ofaccessory 630. Additionally or alternatively, power path controlcircuitry 633 may impose power limits, voltage limits, and/or currentlimits on power, voltage, and/or current, respectively, supplied fromcomputing system 620. In some embodiments, power path control circuitry633 may impose limits on amplitude, frequency, phase, and/or othercharacteristics of a signal, such as an electrical signal and/or anoptical signal, communicated from computing system 620.

As shown in FIG. 10A, power path control circuitry 633 may be providedentirely as part of first connector 631. However, the location of powerpath control circuitry 633 is not so limited. For example, in someembodiments, power path control circuitry 633 may be located entirelybetween first connector 631 and second connector 632, entirely withinsecond connector 632, or have portions that are located in one or moreof first connector 631, second connector 632, and between firstconnector 631 and second connector 632.

Computing system 620 may be any suitable electronic component(s) forproviding power to and/or communicating with host device 610 viaaccessory 630. In one embodiment, computing system 620 includes variouscomponents for both providing power to host device 610 and establishingcommunications with host device 610. For example, computing system 620may include a display 621 for displaying information to a user, a userinterface for receiving inputs from the user including a keyboard 622and a mouse 623, and a housing 624 that is configured to house variouselectronic components for enabling computing system 620 to provide powerto and/or communicate with host device 610. In some embodiments, housing624 may include a processor (not shown), a tangible non-transitorycomputer readable storage medium (not shown), and the like, all operablycoupled to one another such that the processor may execute instructionsstored on the computer readable storage medium so as to cause computingsystem 620 to perform one or more of the operations discussed herein.Housing 624 may also include a connector 625 such as a plug connector ora receptacle connector for mechanically and electrically couplingcomputing system 620 to other electronic components such as host device610. In some embodiments, connector 625 may include one or more pins orconductive contacts for establishing electrical and/or opticalcommunication with corresponding pins or contacts of a second connector632 of accessory 630. Connector 625 may be sized and shaped tomechanically engage with second connector 632 of accessory 630, andsecond connector 632 may be sized and shaped to mechanically engage withconnector 625.

Computing system 620 may include a power source such as a battery (notshown) for providing power to host device 610 via a power pathestablished between the power source and connector 625. In someembodiments, computing system 620 may receive power from a power sourceexternal to computing system 620, such as from an external battery,power generator, and/or wall socket/electrical outlet. In someembodiments, computing system 620 may include power conversion circuitry(not shown) for converting AC power supplied from an external source toDC power consumed by computing system 620 and/or communicated to hostdevice 610 via connector 625.

It should be recognized that embodiments are not limited to requiringhost device 610 to be coupled to a computing system 620. Rather, in someembodiments, host device 610 may be coupled to any suitable electroniccomponent via accessory 630 so as to establish a power path and/orcommunication path between host device 610 and a power source. Forexample, instead of being coupled to computing system 620, host device610 may be coupled to a power source via an electrical socket such asthose provided in a wall, to a battery, to an AC/DC converter whichitself is coupled to an electrical socket, etc.

FIG. 10B illustrates a system 650 for determining whether an accessoryincludes particular circuitry according to a second embodiment of thepresent invention. In this embodiment, system 650 includes host device610 as discussed with reference to FIG. 10A, and accessory 660. Hostdevice 610 may be electrically and mechanically coupleable to accessory660.

Accessory 660, like accessory 630, may be any suitable electronic deviceoperable to establish a power path between host device 610 and a powersource (such as one provided in accessory 660, and/or one providedexternal to accessory 660 but to which accessory 660 is electricallycoupled), and/or operable to establish a communication path between hostdevice 610 and electronic components (such as electronic components ofaccessory 660 and/or electronic components external to accessory 660).For example, accessory 660 may be an alarm clock, a radio, a speakerset, a docking station, an input device such as a keyboard, a musicalinstrument such as a digital piano, a battery, a charging station, animage/video projection unit, etc. Accessory 660 may include componentstypically found in such electronic devices for performing the operationsdiscussed herein. For example, accessory 660 may include a userinterface 661 that may be operable to display information (e.g., acurrent time) to a user and/or receive information (e.g., via atouchscreen), speakers 662 for providing an audio output to a user, aconnector 663 (e.g., a receptacle connector or a plug connector) formechanically, electrically, and/or optically coupling accessory 660 toother electronic components such as host device 610, etc., whereconnector 663 may include one or more pins or conductive contacts forestablishing electrical and/or optical communication with correspondingpins or contacts of a connector coupled to receptacle connector 663,such as connector 615 of host device 610.

Accessory 660 may include a power source such as a battery (not shown)for providing power to host device 610 via a power path establishedbetween the power source and connector 615. In some embodiments,accessory 660 may also or alternatively receive power from a powersource external to accessory 660, such as from an external battery,power generator, and/or wall socket/electrical outlet. In at least oneembodiment, accessory 660 may also include power conversion circuitry(not shown) for converting AC power supplied from an external source toDC power consumed by accessory 660 and/or communicated to host device610 via connector 663.

Accessory 660 may also include power path control circuitry 664 whichmay be any suitable hardware and/or software for controlling a powerpath and/or communication path between a power source and connector 663.Since power path control circuitry 664 is operable to control a powerpath and/or communication path between a power source and receptacleconnector 663, power path control circuitry 664 may also be operable tocontrol a power path and/or communication path between devices that maybe mechanically, electrically, and/or optically coupled to receptacleconnector 663 of accessory 660, such as host device 610. Power pathcontrol circuitry 664 may control the power path between the powersource and host device 610 in any one or more of a number of fashions.In one embodiment, power path control circuitry 664 may operate similarto power path control circuitry 633. For example, power path controlcircuitry 664 may be operable to alter a characteristic of the powerpath, such as electrical impedance, voltage capacity, current capacity,and the like of accessory 660. Additionally or alternatively, power pathcontrol circuitry 664 may impose power limits, voltage limits, and/orcurrent limits on power, voltage, and/or current supplied from the powersource and/or other components of accessory 660. In some embodiments,power path control circuitry 664 may impose limits on amplitude,frequency, phase, and/or other characteristics of a signal, such as anelectrical signal and/or an optical signal, communicated from the powersource and/or other components of accessory 660.

Systems 600 and 650 in certain embodiments are systems for determiningwhether an accessory includes particular circuitry such as powerlimiting circuitry. However, it will be appreciated by those of ordinaryskill in the art that such systems could operate equally well with feweror a greater number of components than are illustrated in FIGS. 10A and10B. Further, those of ordinary skill in the art would recognize thatthe systems could operate equally well where the components of thesystems, such as host device 610 and accessory 630/660, have fewer or agreater number of components than are illustrated in FIGS. 10A and 10B.Thus, the depiction of systems 600 and 650 in FIGS. 10A and 10B shouldbe taken as being illustrative in nature, and not limiting to the scopeof the disclosure.

FIG. 11A illustrates a plug connector 700 according to an embodiment ofthe present invention. Plug connector 700 is an example of a plugconnector used herein to explain various embodiments of the presentinvention. Plug connector 700 may correspond, for example, to connector112 and/or connector 122 (FIG. 1), and may be operatively mated to acorresponding receptacle connector in either of two orientations 180degrees rotated from each other. One skilled in the art will realizethat many other forms and types of connectors other than plug connector700 can be used and that techniques described herein will apply to anyplug connector that has the characteristics of plug connector 100.

Plug connector 700 includes a body 702 and a tab portion 704. A cable706 is attached to body 702 and tab portion 704 and extends away frombody 702 in a direction parallel to the length of the connector 700. Tab704 is sized to be inserted into a corresponding receptacle connectorduring a mating event and includes a first contact region 708 a formedon a first major surface 710 a and a second contact region 708C (notshown in FIG. 11A) formed at a second major surface 710 b oppositesurface 710 a. A plurality of contacts 712 can be formed in each ofcontact regions 708 a and 708C such that, when tab 704 is inserted intoa corresponding receptacle connector, contacts 712 in regions 708 aand/or 708C are electrically coupled to corresponding contacts in thereceptacle connector. In some embodiments, contacts 712 areself-cleaning wiping contacts that, after initially coming into contactwith a receptacle connector contact during a mating event, slide furtherpast the receptacle connector contact with a wiping motion beforereaching a final, desired contact position.

FIG. 11B illustrates a simplified, cross-sectional view of plugconnector 700. The front view illustrates a cap 720. Cap 720 can be madefrom a metal or other conductive material and can extend from the distaltip of connector 700 along the side of the connector towards body 702either fully or partially surrounding contacts 712 formed in contactregions 708 a and 708C in the X and Y directions. In some embodiments,cap 720 can be grounded in order to minimize interference that mayotherwise occur on contacts 712 of connector 700 and can thus bereferred to as a ground ring. Contacts 712 ₍₁₎-712 _((N)) can bepositioned within contact region 708 a and additional contacts 714₍₁₎-714 _((N)) can be positioned within region 708C on the opposingsurface of tab 704. In some embodiments, N can be between 2 and 8.

FIG. 11C illustrates a cross-sectional schematic view of contacts 712,714 and positioning of the contacts. Contacts 712, 714 can be mounted oneither side of a PCB 750. In some embodiments, contacts 712, 714 arepart of a reversible or dual orientation unpolarized plug connector thatcan be mated with a corresponding receptacle connector in either of twoorientations. In other embodiments, contacts 712, 714 are part of apolarized plug connector that can be mated with a correspondingreceptacle connector in only a single orientation. Contacts 712, 714 canbe made from a copper, nickel, brass, a metal alloy or any otherappropriate conductive material. In some embodiments, spacing may beconsistent between each of the contacts on the front and back sides andbetween the contacts and the edges of the connector providing 180 degreesymmetry so that plug connector 700 can be inserted into andelectrically mated with a corresponding receptacle connector in eitherof two orientations. When connector 700 is properly engaged with areceptacle connector, each of contacts 712 ₍₁₎-712 _((N)) (and/or 714₍₁₎-714 _((N)) is in electrical connection with a corresponding contactof the receptacle connector.

It should be recognized that embodiments are not limited to a plugconnector including contacts mounted on opposite sides. Rather, in someembodiments, contacts may be mounted on only one side of the plugconnector. FIG. 11D illustrates an embodiment where contacts 714 ₍₁₎-714_((N)) are mounted on only one side of PCB 150. In such a case, whenconnector 700 is properly engaged with a receptacle connector, each ofcontacts 714 ₍₁₎-714 _((N)) are in electrical connection with acorresponding contact of the receptacle connector.

FIG. 11E illustrates a pin-out configuration for connector 700 accordingto one particular embodiment of the present invention as described inconnection with FIG. 11C above.

The pin-out shown in FIG. 11E includes four contacts 712(4), 712(5),714(4), and 714(5) that are electrically coupled together to function asa single contact dedicated to carrying power to a connected host device.Connector 700 may also include accessory ID contacts 712(8) and 714(8);accessory power contacts 712(1) and 714(1); and eight data contactsarranged in four pairs. The four pairs of data contacts may be (a)712(2) and 712(3), (b) 712(6) and 712(7), (c) 714(2) and 714(3), and (d)714(6) and 714(7). Host power contacts 712(4), 112(5), 714(4), and714(5) carry power from an accessory associated with connector 700 to aportable electronic device that is coupled to the accessory viaconnector 700. The host power contacts can be sized to handle anyreasonable power requirement for an electronic device or host device,and for example, can be designed to carry between 3-20 Volts from anaccessory to charge the portable electronic device connected toconnector 700. In this embodiment, host power contacts 712(4), 712(5),714(4), and 714(5) are positioned in the center of contact regions 708a, 708 b to improve signal integrity by keeping power as far away aspossible from the sides of ground ring 705.

Accessory power contacts 712(1) and 714(1) can be used for an accessorypower signal that provides power from the electronic device (i.e. thehost device) to an accessory. The accessory power signal is typically alower voltage signal than the host power in signal received over hostpower contacts 712(4) and 712(5), for example, 3.3 volts as compared to5 volts or higher. The accessory ID contacts provide a communicationchannel that enables the host device to authenticate the accessory andenable the accessory to communicate information to the host device aboutthe accessory's capabilities as described in more detail below.

The four pairs of data contacts (a) 712(2) and 712(3), (b) 712(6) and712(7), (c) 714(2) and 714(3), and (d) 714(6) and 714(7) may be used toenable communication between the host and accessory using one or more ofseveral different communication protocols. For example, data contacts712(2) and 712(3) are positioned adjacent to and on one side of thepower contacts, while data contacts 712(6) and 712(7) are positionedadjacent to but on the other side of the power contacts. A similararrangement of contacts can be seen for contacts 714 on the othersurface of the PCB. The accessory power and accessory ID contacts arepositioned at each end of the connector. The data contacts can be highspeed data contacts that operate at a rate that is two or three ordersof magnitude faster than any signals sent over the accessory ID contactwhich makes the accessory ID signal look essentially like a DC signal tothe high speed data lines. Thus, positioning the data contacts betweenthe power contacts and the ID contact improves signal integrity bysandwiching the data contacts between contacts designated for DC signalsor essentially DC signals.

FIG. 11F illustrates a pin-out configuration for a connector 701according to another particular embodiment of the present invention.

Connector 701 is also a reversible connector just like connector 700. Inother words, based on the orientation in which connector 701 is matedwith a corresponding connector of a host device, either the contacts onthe surface 708 a or 708 b are in physical and electrical contact withthe contacts in the corresponding connector of the host device. Asillustrated in FIG. 11F, connector 701 may have eight contacts arrangedon an upper surface 750 a of a PCB 750 and eight contacts arranged on alower surface 750 b of PCB 750.

Connector 701 includes two contacts 712(1) and 714(4) that can functionas accessory ID contacts to carry the identification signals between theaccessory and the portable electronic device. Contacts 712(1) and 714(4)are electrically connected to each other as illustrated in FIG. 11F.Connector 701 can have four pairs of data contacts, (a) 712(2) and712(3), (b) 712(6) and 712(7), (c) 714(2) and 714(3), and (d) 714(6) and714(7). In this particular embodiment, opposing data contacts, e.g.,712(2) and 714(2), are electrically connected to each other via PCB 750as illustrated in FIG. 11E. Connector 701 may further include host powercontacts 712(4) and/or 714(5) that may be electrically connected to eachother. Host power contacts 712(4) and 714(5) can carry power to the hostdevice that is mated with connector 701. For example, plug connector 701may be part of a power supply system designed to provide power to thehost device. In this instance, either contact 712(4) or 714(5) may carrypower from the power supply to the host device, e.g., to charge abattery in the host device.

Connector 701 may further include accessory power contacts 712(5) and714(8) that may be electrically connected to each other, e.g., via PCB750. Accessory power contacts carry power from the host device to aconnected accessory. For example, in some instances, an accessoryconnected to the host device may not be self-powered and may derive itspower from the host device. In this instance, the host device can supplypower to the accessory over either of the accessory contacts, dependingon the orientation of connector 701 with respect to a correspondingconnector of the host device. Connector 701 may further include twoground contacts 712(8) and 714(1) electrically connected to each other.The ground contacts provide a ground path for connector 701.

FIG. 12A illustrates a receptacle connector 800 according to anembodiment of the present invention. Receptacle connector 800 is anexample of a receptacle connector used herein to explain variousembodiments of the present invention. Receptacle connector 800 maycorrespond, for example, to connector 112 and/or connector 122 (FIG. 1),and in some embodiments is used to match plug connector 700. One skilledin the art will realize that many other forms and types of connectorsother than receptacle connector 800 can be used.

Receptacle connector 800 includes a housing 802 that defines a cavity804 and houses N contacts 806 ₍₁₎-806 _((N)) within the cavity. Inoperation, a connector plug, such as plug connector 700 (or connector701) can be inserted into cavity 804 to electrically couple the contacts712 ₍₁₎-712 _((N)) and/or 714 ₍₁₎-714 _((N)) to respective contacts 806₍₁₎-806 _((N)). Each of the receptacle contacts 806 ₍₁₎-806 _((N))electrically connects its respective plug contact to circuitryassociated with the electrical device in which receptacle connector 800is housed. For example, receptacle connector 800 can be part of aportable media device (e.g., host device 110) and electronic circuitryassociated with the media device is electrically connected to receptacle800 by soldering tips of contacts 806 ₍₁₎-806 _((N)) that extend outsidehousing 802 to a multilayer board such as a printed circuit board (PCB)within the portable media device. Note that receptacle connector 800 isdesigned to be mated with a dual orientation, reversible plug connectorand includes contacts on just a single side so the receptacle connector(and the electronic device the receptacle connector is part of) can bemade thinner. In other embodiments, connector 800 may have contacts oneach side while connector 700 may only have contacts on a single side oron both sides.

FIG. 12B illustrates a cross section view of receptacle connector 800according to an embodiment of the present invention. As illustrated, insome embodiments, additional contacts 808 ₍₁₎ and 808 ₍₂₎ are located ateither ends of contacts 806 ₍₁₎-806 _((N)). Contacts 808 ₍₁₎ and 808 ₍₂₎may be used to detect whether the plug connector is fully inserted intocavity 804 or inserted to a point where contacts 712 (or 714) of plugconnector 700 (or connector 701) are physically coupled to contacts 806of receptacle connector 800. In some embodiments, contacts 808 ₍₁₎ and808 ₍₂₎ can also be used to detect whether the plug connector has beendisconnected from the receptacle connector. In some embodiments,contacts 808 can make contact with cap 720 of plug connector 700 whenthe plug connector is inserted beyond a certain distance within cavity804. In some embodiments, contacts 808 are placed such that they willmake contact with the ground ring of plug connector only when contacts712 make a solid physical connection with contacts 806. In someembodiments, when contacts 808 connect to the ground ring of the plugconnector, a signal may be generated indicating the connection.

In some embodiments, receptacle connector 800 may have contacts both onthe top side and the bottom side of cavity 804. FIG. 12C illustrates across-sectional view of a receptacle connector 850 that includescontacts 806 ₍₁₎-806 _((N)) on the top and contacts 806 ₍₁₎-806 _((N))on the bottom. In some embodiments, a plug connector with electricallyisolated contacts on the top and the bottom side may use the receptacleconnector 850 of FIG. 14C.

In some embodiments, receptacle connector 850 may have contacts 806_((1)-(N)) only on a single side inside cavity 804 as described above.In a particular embodiment, receptacle connector may have eight (8)contacts 806 ₍₁₎-806 ₍₈₎ as illustrated in FIG. 12D. Some or all ofthese contacts may be configured to perform one of several functionsdepending on the signals available on a plug connector. Plug connector700 (or connector 701) may be associated with any one of severalaccessories (e.g., accessory 120) that may be designed to work with ahost device (e.g., host device 110) that is associated with receptacleconnector 850. For example, plug connector 700 (or connector 701) may beassociated with an audio only accessory in which case the signalsavailable on the contacts, e.g., 706 ₍₁₎-706 _((N)), of the plugconnector may include audio and related signals. In other instances,where plug connector 700 (or connector 701) is associated with a morecomplex accessory such as video accessory, the contacts of plugconnector may carry audio, video, and related signals. Thus, in order toenable receptacle connector 850 to be operable with various differenttypes of signal, contacts 806 ₍₁₎₋₍₈₎ of receptacle connector 850 can bemade configurable based on the signals available from a plug connector700(or connector 701). In at least one embodiment, one or more contactsof plug connector 700 may be operable to send or receive power from apower source as already described herein, and one or more contacts ofplug connector 700 may be operable to communicate information and/orvarious requests (and in some cases, simultaneously with power via thesame pin) as already described herein. Similarly, one or more contactsof receptacle connector 800 may be operable to send or receive powerfrom a power source as already described herein, and one or morecontacts of receptacle connector 800 may be operable to communicateinformation and/or various requests (and in some cases, simultaneouslywith power via the same pin) as already described herein.

In the particular embodiment illustrated in FIG. 12D, receptacleconnector 850 has eight contacts 806 ₍₁₎₋₍₈₎ in addition to twoconnection detection contacts 808 ₍₁₎ and 808 ₍₂₎. The operation of theconnection detection contacts 808 ₍₁₎ and 808 ₍₂₎ is described above inrelation to FIG. 12B. Some or all of contacts 806 ₍₁₎₋₍₈₎ have anassociated switch that can configure the contact to carry one of manypossible signals. However, for ease of explanation only one switch 820coupled to contact 806 ₍₈₎ is illustrated in FIG. 12D. It is to be notedthat some or all of the other contacts 806 ₍₁₎-806 ₍₈₎ may each have asimilar switch 820 coupled to it. As illustrated in FIG. 12D, switch 820can be used to configure contact 806 ₍₈₎ to carry any one of signalsS₁-S_(N) depending on the configuration of the plug connector.

In a particular embodiment, contact 206 ₍₁₎ may be an identification buspins (ACC_(—)1) and can be configured to communicate a command operableto cause an accessory to perform a function and provide a response to ahost device unique to the command. The command may be any one or more ofa variety of commands, including a request to identify a connector pinand select one of a plurality of communication protocols forcommunicating over the identified connector pin, a request to set astate of the accessory, and a request to get a state of the accessory.Contact 206 ₍₁₎ may also or alternatively be configured to communicatepower from the host device to the accessory (e.g., Acc_Pwr). Forexample, contact 206 ₍₁₎ may be coupled to a positive (or negative)voltage source within the host device so as to generate a voltagedifferential with another pin (such as a ground pin which may be, e.g.,contact 206 ₍₈₎). In a particular embodiment, contact 806 ₍₁₎ maycorrespond to data pin 114 and can be configured to carry one of (a)accessory identification signals, (b) accessory power, (c) host deviceidentification signals, and (d) requests for identification signals. Inother words, signals S₁-S_(N) can any be selected from these signals forcontact 806 ₍₁₎ by its corresponding switch 820.

In a particular embodiment, contacts 806 ₍₂₎ and 806 ₍₃₎ may correspondto additional data pins 115 and can each be configured to carry one of avariety of signals, such as (a) USB differential data signals, (b)non-USB differential data signal, (c) UART transmit signal, (d) UARTreceive signal, (e) digital debug input/output signals, (f) a debugclock signal, (g) audio signals, (h) video signals, etc.

In a particular embodiment, contact 806 ₍₄₎ may carry incoming power(e.g., a positive voltage relative to another contact such as a groundpin) to the host device (e.g., from a power source in or coupled to theaccessory) with which receptacle connector 800 is associated. Contact806 ₍₅₎ may also function as an identification bus pin (ACC_ID) similarto contact 806 ₍₁₎ described above. Contact 806 ₍₅₎ may also oralternatively be configured to communicate power from the host device tothe accessory (e.g., Acc_Pwr), depending on the orientation of aconnected plug connector 700 (or connector 701) with respect toreceptacle connector 800.

In a particular embodiment, contacts 806 ₍₆₎ and 806 ₍₇₎ may form asecond pair of data pins (DP2/DN2) and can each be configured to carryone of (a) USB differential data signals, (b) Non-USB differential datasignal, (c) UART transmit signal, (d) UART receive signal, (e) digitaldebug input/output signals, (f) a debug clock signal, (g) audio signals,(h) video signals, etc.

In a particular embodiment, contact 806 ₍₈₎ may be a ground pin orotherwise provided at a voltage potential lower than contacts 806 ₍₁₎,806 ₍₄₎, and 806 ₍₅₎ so as to provide a voltage potential for powerbeing provided to or from the host device.

In some embodiments, tab 704 has a 180 degree symmetrical, doubleorientation design which enables plug connector 700 (or connector 701)to be inserted into receptacle 800 in both a first orientation and asecond orientation. Connector 700 (or connector 701) can be mated withconnector 800 where contacts 712 of connector 700 can couple withcontacts 806 of connector 800. We can refer to this as the firstorientation for purposes of explanation. Details of several particularembodiments of connector 700 (or connector 701) are described in acommonly-owned U.S. patent application Ser. No. 13/607,366 titled“DUAL-ORIENTATION ELECTRONIC CONNECTOR”, filed on Sep. 7, 2012, thecontents of which are incorporated by reference herein in their entiretyfor all purposes.

In some embodiments, connector 700 (or connector 701) can be mated withconnector 800 in a second orientation. In the second orientation,contacts 714 of connector 700 are coupled with contacts 806 of connector800. The second orientation may be 180 degrees rotated from the firstorientation. However, these are not the only possible orientations. Forexample, if connector 700 (or connector 701) is a square connector witha corresponding square connector 800, then connector 700 (or connector701) can be mated with connector 800 in one of four possibleorientations. Thus, one skilled in the art will realize that more thantwo orientations for the connectors may be possible.

FIGS. 12E and 12F illustrate pin-out configuration for a receptacleconnector according to two different embodiments of the presentinvention. In one embodiment, receptacle connector 800 has a pin-out asshown in FIG. 12E that matches the pin-out of connector 700 in FIG. 11Eand in another embodiment receptacle connector 800 has a pin-out asshown in FIG. 12F that matches pin-out of connector 701 of FIG. 11F. Ineach of FIGS. 12E and 12F, the ACC1 and ACC2 pins are configured to matewith either the accessory power (ACC_PWR) or accessory ID (ACC_ID) pinsof the plug connector depending on the insertion orientation of plugconnector, the pair of Data A contacts is configured to mate with eitherthe pair of Data 1 contacts or the pair of Data 2 contacts of the plugconnector, and the P_IN (power in) pin or pins are configured to matewith the Host Power contact or contacts of the plug connector.Additionally, in the pin-out of FIG. 12F, the GND contact is configuredto mate with the GND contact in the plug connector.

Connectors 700 and 800 in certain embodiments are reversible connectorswith exposed electrical contacts with a number of components. However,it will be appreciated by those of ordinary skill in the art that suchconnectors could operate equally well with fewer or a greater number ofcomponents than are illustrated in FIGS. 11A to 12F. Thus, the depictionof connectors 700 and 800 in FIGS. 11A to 12F should be taken as beingillustrative in nature, and not limiting to the scope of the disclosure.

Various embodiments of systems, methods, and apparatus for determiningthe whether an accessory includes particular circuitry have beendescribed. While these embodiments have been described in the context ofFIGS. 1 to 12F, many modifications and variations are possible. Theabove description is therefore for illustrative purposes and is notintended to be limiting. Also, references to top or bottom, or front andback of the various structures described above are relative and are usedinterchangeably depending on the point of reference. Similarly,dimensions and sizes provided throughout the above description are forillustrative purposes only and the inventive concepts described hereincan be applied to structures with different dimensions. Accordingly, thescope and breadth of the present invention should not be limited by thespecific embodiments described above and should instead be determined bythe following claims and their full extend of equivalents.

1. A host device comprising: a connector including: a power contactoperable to receive a voltage from an accessory, the power contactforming part of a power path between the host device and the accessory;and a data contact operable to exchange data with the accessory; andcontrol circuitry coupled to the connector and operable to: measure afirst voltage received from the accessory via the power contact; send aninstruction to the accessory via the data contact, the instructioninstructing the accessory to alter an impedance, at the accessory, ofthe power path between the host device and the accessory; sink currentfrom the accessory via the power contact; measure a second voltagereceived from the accessory via the power contact after sending theinstruction instructing the accessory to alter the impedance of thepower path and after sinking current from the accessory; and determinewhether the accessory includes particular circuitry based on whether thefirst voltage is different than the second voltage.
 2. The host deviceof claim 1 wherein the control circuitry is further operable todetermine that the accessory includes the particular circuitry if thefirst voltage is greater than the second voltage by at least apredetermined amount, and to determine that the accessory does notinclude the particular circuitry if the first voltage is not greaterthan the second voltage by at least the predetermined amount.
 3. Thehost device of claim 1 wherein the control circuitry is further operableto charge the host device using power received at the power contact whenit is determined that the accessory includes the particular circuitry.4. The host device of claim 3 further comprising an internal battery,wherein being operable to charge the host device includes being operableto couple the power contact to the internal battery.
 5. The host deviceof claim 1 wherein the control circuitry is further operable to preventcharging of the host device from power received at the power contactwhen it is determined that the accessory does not include the particularcircuitry.
 6. The host device of claim 1 further comprising a currentsink coupled to the power contact and the control circuitry, the currentsink being operable to sink current from a power source provided at theaccessory via the power contact.
 7. The host device of claim 1 furthercomprising a current sink coupled to the power contact and the controlcircuitry, the current sink being operable to sink current from a powersource provided external to the accessory via the power contact.
 8. Thehost device of claim 1 further comprising: power control circuitryincluding an overvoltage protection switch and a processor; and a chargecontrol switch coupled between the power control circuitry and the powercontact; wherein the processor is operable to: control the chargecontrol switch to control charging of an internal battery of the hostdevice, and control the overvoltage protection switch to prevent theinternal battery from receiving a charging voltage from the powercontact when at least one of the first voltage or the second voltage isgreater than a predetermined voltage.
 9. A method of determining whetheran accessory includes particular circuitry, comprising: measuring, at afirst contact of a host connector associated with a host device, a firstvoltage received from the accessory, the first voltage being receivedvia the first contact, wherein the first contact forms part of a powerpath between the host device and the accessory; sending, by the hostdevice, an instruction to the accessory over a second contact of thehost connector to alter an impedance, at the accessory, of the powerpath between the host device and the accessory; sinking, by the hostdevice and via the first contact, current from the accessory; receiving,by the host device and over the first contact, a second voltage from theaccessory in response to sending the instruction; measuring, by the hostdevice at the first contact, after sending the instruction to theaccessory to alter the impedance of the power path between the hostdevice and the accessory, and after sinking current from the accessory,the second voltage received from the accessory; and determining, by thehost device, whether the accessory includes particular circuitry basedon whether the first voltage is different than the second voltage. 10.The method of claim 9 wherein sinking current includes sinking currentfrom a power source located at the accessory or external to theaccessory.
 11. The method of claim 10, wherein the amount of currentsinked is sufficient to cause the second voltage to be less than thefirst voltage when the accessory includes the particular operatingcircuitry and the particular operating circuitry is operating in a statethat alters the impedance of the power path between the host device andthe accessory.
 12. The method of claim 9 wherein determining whether theaccessory includes particular circuitry comprises: determining that theaccessory includes the particular circuitry if the second voltage isless than the first voltage by at least a predetermined amount; anddetermining that the accessory does not include the particular circuitryif the second voltage is not less than the first voltage by at least thepredetermined amount.
 13. The method of claim 9 further comprising: ifthe accessory is determined to include the particular circuitry,coupling the first contact to power control circuitry of the host devicethat is operable to charge the host device using power received from theaccessory.
 14. The method of claim 9 further comprising: if theaccessory is determined to not include the particular circuitry,preventing the host device from charging using power received from theaccessory.
 15. The method of claim 9 wherein sending an instruction tothe accessory comprises one of: sending a first instruction instructingthe accessory to operate in a first state in which an output voltagefrom the accessory is substantially unaltered from an input voltagereceived by the accessory from a power source; sending a secondinstruction instructing the accessory to operate in a second state inwhich the output voltage from the accessory is lower than the inputvoltage; or sending a third instruction instructing the accessory tooperate in a third state in which the output voltage is reduced by apredetermined amount from the input voltage.
 16. An accessorycomprising: a power pin operable to provide a voltage to a host device;a data pin operable to receive an instruction from the host device; andpower limiting circuitry configured to implement: a bypass mode ofoperation in which current and voltage may pass through the powerlimiting circuitry from a power source to the power pin substantiallyunaltered, and a power limiting mode of operation in which an impedanceof the power limiting circuitry is increased compared to when operatingin the bypass mode of operation so as to reduce a first voltage receivedfrom the power source to a second voltage provided at the power pin;wherein the power limiting circuitry switches from the bypass mode ofoperation to the power limiting mode of operation in response toreceiving an instruction from the host device over the data pin.
 17. Theaccessory of claim 16 wherein the power limiting circuitry includesidentification circuitry and impedance altering circuitry, the impedancealtering circuitry being arranged between the power source and the powerpin and being configured to operate in the bypass mode of operation andthe power limiting mode of operation, the identification circuitry beingcoupled to the impedance altering circuitry and the data pin.
 18. Theaccessory of claim 17 wherein the identification circuitry is operableto instruct the impedance altering circuitry to operate in the powerlimiting mode of operation so as to disable a power path between thepower source and the host device via the power pin in response toreceiving power from the host device over the data pin.
 19. Theaccessory of claim 18 wherein the identification circuitry is furtheroperable to: read a request for an accessory identifier received fromthe host device over the data pin while the power limiting circuitry isin the power limiting mode of operation; determine whether the requestfor the accessory identifier is valid; and instruct the impedancealtering circuitry to switch its mode of operation from the powerlimiting mode of operation to the bypass mode of operation so as toenable the power path between the power source and the host device viathe data pin in response to determining that the request for theaccessory identifier is valid.
 20. The accessory of claim 17 wherein theidentification circuitry is operable to: receive an instruction from thehost device over the data pin; determine whether the instruction is aninstruction to alter an impedance of a power path between the powersource and the host device; and cause the impedance altering circuitryto operate in one of the bypass mode of operation or the power limitingmode of operation so as to alter the impedance of the power path betweenthe power source and the host device via the power pin in response todetermining that the instruction is an instruction to alter theimpedance of the power path between the power source and the hostdevice.
 21. The accessory of claim 16 wherein the power limitingcircuitry operates in the bypass mode of operation in response to theaccessory establishing a physical connection with the host device. 22.The accessory of claim 21 wherein the power limiting circuitry operatesin the bypass mode of operation until receiving a voltage from the hostdevice over the data pin, and the power limiting circuitry switches itsmode of operation from the bypass mode of operation to the powerlimiting mode of operation in response to receiving a positive voltagefrom the host device over the data pin.
 23. The accessory of claim 16wherein the power limiting circuitry, when in the power limiting mode ofoperation, has a voltage/current characteristic such that the powerlimiting circuitry outputs a positive voltage an amount of currentpassing through the power limiting circuitry is less than a thresholdamount of current and outputs approximately zero voltage when the amountof current passing through the power limiting circuitry meets or exceedsthe threshold amount of current.
 24. A method of operating an accessory,comprising: receiving, at the accessory, an instruction from a hostdevice, the instruction being received over a data pin of the accessory,the data pin being coupled to identification circuitry of the accessory;determining, by the identification circuitry, whether the instruction isan instruction to alter an impedance of a power path between a powersource and the host device, the power path between the power source andthe host device including power limiting circuitry disposed between thepower source and the host device and coupled to the identificationcircuitry; and altering the impedance of the power path between thepower source and the host device by sending a control signal from theidentification circuitry to the power limiting circuitry that causes thepower limiting circuitry to change its mode of operation between abypass mode of operation and a power limiting mode of operation when itis determined that the instruction is an instruction to alter theimpedance of the power path between the power source and the hostdevice.
 25. The method of claim 24, wherein altering the impedance ofthe power path includes increasing or decreasing the impedance of thepower path between the power source and the host, the impedance of thepower path being increased when the power limiting circuitry changes itsmode of operation from the bypass mode of operation to the powerlimiting mode of operation, and the impedance of the power path beingdecreased when the power limiting circuitry changes its mode ofoperation from the power limiting mode of operation to the bypass modeof operation.
 26. The method of claim 25, wherein the impedance of thepower path is increased only when an amount of current passing throughthe power limiting circuitry exceeds a threshold amount of current. 27.The method of claim 24, further comprising: determining whether theaccessory is mated with the host device; and in response to determiningthat the accessory is mated with the host device, operating the powerlimiting circuitry in the bypass mode of operation so as to enable thepower path between the power source and the host device.
 28. The methodof claim 27, further comprising: determining whether power is receivedfrom the host device via the data pin of the accessory; and in responseto determining that power is received from the host device via the datapin of the accessory, operating the power limiting circuitry in thepower limiting mode of operation so as to disable the power path betweenthe power source and the host device.
 29. The method of claim 28,further comprising: receiving a request for an accessory identifier fromthe host device over the data pin of the accessory; determining whetherthe request for the accessory identifier is valid; and upon determiningthat the request for the accessory identifier is valid: operating thepower limiting circuitry in the bypass mode of operation so as to enablethe power path between the power source and the host device; andcommunicating the accessory identifier to the host device via the datapin.
 30. The method of claim 29, further comprising: receiving aninstruction to disable the power path between the power source and thehost device; and in response to receiving the instruction to disable thepower path between the power source and the host device, operating thepower limiting circuitry in the power limiting mode of operation so asto disable the power path between the power source and the host device.